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Tach says 1500, TPRT says 1,000-1,025 by 87FieroSport
Started on: 01-01-2014 10:31 PM
Replies: 41 (750 views)
Last post by: bcampbell on 01-10-2014 10:19 PM
87FieroSport
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Report this Post01-01-2014 10:31 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
I finally got TunerPro RT to work with me after a few months.
I decided to do a quick test.

On cold startup Tuner Pro says my idle is 1,000-1,025. But my tach reads 1500 or so.

My IAC also says Steps: 95 on cold start up.

I plan to run this on my way to work to get a good reading after everything is warmed up. Could someone direct me to what the values of everything should be
with a good-running 2.8L?

BLM
IAC
TPS (Idle in park, mine says 1.00v)
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jb1
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Report this Post01-01-2014 10:34 PM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Tach very well could be off..

------------------


87GTseries 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
Northstar Rebuild

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87FieroSport
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Report this Post01-01-2014 10:41 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
Could be.
I'm new to reading data off of a computer, Are Tunerpro's values straight from the ECM?

Should I abide by them, and do secondary tests to confirm Tunerpro's values?

My engine "seems" to idle faster on cold startup, it feels like it actually is 1500RPM, but when I saw TPRT, it was fine.
Would my timing be off? (I don't have a timing light at the moment.)

Would TP allow me to determine if my timing is off? (By looking into other values?)
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Report this Post01-01-2014 10:46 PM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
yes the values on the tuner pro are from the ecm, that is why I would guess tach is off.
I have never used Tuner pro ,but It should tell you if timing is being advanced or retarded and by how many degrees from tdc.
Someone that knows a lot more than I do will be along soon and hopefully answer your questions better, but as far as rpm the tuner pro is more accurate
and would be what I went by over the tach.

------------------


87GTseries 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
Northstar Rebuild

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87FieroSport
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Report this Post01-01-2014 10:53 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well another general question;

Since my tach is reading 1500, would that increase fuel consumption?
Or would that not even matter since its not actually the signal that's off.
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jb1
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Report this Post01-01-2014 10:56 PM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
will not affect fuel mileage at all. just a guage. with a resistor you can make it read whatever you want it to read..

------------------


87GTseries 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
Northstar Rebuild

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fieroall
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Report this Post01-02-2014 01:49 PM Click Here to See the Profile for fieroallSend a Private Message to fieroallEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds like you've got a 4 cyl gauge cluster in a V6 car. I have the same problem. Bout to change the capacitor to fix it.
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Report this Post01-02-2014 01:56 PM Click Here to See the Profile for DooberSend a Private Message to DooberEdit/Delete MessageReply w/QuoteDirect Link to This Post
That or the electronics on the tach are on their way out... seen it happen on quite a few '80s cars (G-Bodies, F-Bodies, Fieros...).
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lou_dias
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Report this Post01-02-2014 01:57 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
on my v6 running DIS, the gauge was off about 300-400 rpm (higher) ... this was compared to the sensor they attach to a wire for my dyno runs...

over time they just get less accurate, it seems...
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Report this Post01-02-2014 03:53 PM Click Here to See the Profile for css9450Click Here to Email css9450Send a Private Message to css9450Edit/Delete MessageReply w/QuoteDirect Link to This Post
There is a resistor on the circuit board for the tach, that deteriorates over time and makes the tach read higher and higher. Lots of cars have this problem - probably any GM (with a tach) from the 70s or 80s. My Fiero tach read close to double the correct numbers. There is a fix posted on here somewhere for it; it involves replacing the suspect resistor with a variable resistor and tuning it to match the correct RPMs.

[This message has been edited by css9450 (edited 01-02-2014).]

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87FieroSport
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Report this Post01-02-2014 06:46 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
No. I have a v6 tach
It probably is going, who knows. If I had a spare I'd confirm it.

Does anyone else know how to properly read all the values of TP?
I was reading 660 on my o2 sensor today?
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Report this Post01-02-2014 07:05 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 87FieroSport:

No. I have a v6 tach
It probably is going, who knows. If I had a spare I'd confirm it.

Does anyone else know how to properly read all the values of TP?
I was reading 660 on my o2 sensor today?

Look at the Brightside! You could have paid THOUSANDS for a 4.9 swap only to have it shipped back to you reading 33% higher because changing that resistor was way more effort than what you paid for... [looks at his 4.9 fiero] sigh...
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Report this Post01-02-2014 10:39 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
Once the O2 sensor is warmed up it should jump around quickly between ~100mV and 8-900mV.
While it's cold, mine reads ~445 mV. YMMV.

The ideal BLM is 128, but you'll seldom see exactly 128. It will likely bounce around between 124 and 132, but should spend most of it's time right around 128. If it's consistently off to one direction, there is something else going on.
If it sits constantly at 120 or 136, there is definitely something going on. (Too much or too little fuel being reported.)
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87FieroSport
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Report this Post01-02-2014 10:55 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
Confirmed:

My o2 sensor bounces back and forth (between 100-900mv.)
My INT and BLM seems to stay in the 140's consistently. Sometimes 120, then to 139-140.
My INT and BLM were between 128-144 (Jumped together at the same time from 120-142 a few times. Max 146 I think. (INT was 146 too.)
Coolant temp never rose above 200.

This is all under load between 35-50MPH.
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Report this Post01-02-2014 11:58 PM Click Here to See the Profile for project34Send a Private Message to project34Edit/Delete MessageReply w/QuoteDirect Link to This Post
Earlier this evening, five hours after I'd most recently driven my Fiero, it was a "balmy" 0oF outside. That represented an opportunity to check and record "cold-start" and "post-cold-start" RPMs for my Fiero.

87FieroSport, you'd mentioned...

 
quote
Originally posted by 87FieroSport:
On cold startup...my tach reads 1500 or so.

Same here (at "cold-start" idle, and while in "Park").

Later, as my Fiero's engine began evidencing some warm-up while still at idle (via the temperature gauge needle starting to move rightward), engine tach RPMs gradually declined, essentially stepwise, in approximately 100-RPM increments.

And finally, when the engine reached normal operating temperature, engine tach RPMs at idle (while in Park) stabilized at around 950 to 1000.

You mentioned:

 
quote
Originally posted by 87FieroSport:
My engine "seems" to idle faster on cold startup, it feels like it actually is 1500RPM....

My Fiero's engine does idle faster at cold-start (at around 1500 tach-indicated RPM) than it does after warming up (post-cold-start, tach-indicated RPMs decline to around 950 to 1000 RPM).

You'd asked:

 
quote
Originally posted by 87FieroSport:
...do secondary tests to confirm Tunerpro's values?

I think it would be prudent to record and compare four numbers: TunerPro-indicated RPMs first, and tach-indicated RPMs second --- under "cold-start" and then "post-cold-start" conditions.

Long story short, I'm not yet convinced that your tach-indicated RPMs at "cold-start" and then "post-cold-start" idle conditions are wrong, but your TunerPro-indicated RPMs are right: For example, a tach-indicated 1500 RPM at "cold-start" idle --- when the engine is still stone cold --- doesn't seem especially high to me.

[This message has been edited by project34 (edited 01-03-2014).]

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Report this Post01-03-2014 12:33 AM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes, Fiero V6's "stock" idle at 1500 until a certain temperature is reached.
In my '7730 conversion, I actually programmed this down to 1250, I believe, with a warm idle of 800rpm.

I actually have to keep reminding myself that my tach is off because it cold starts to 1600 and idles around 1100 on the TACH but in actuality, it's where I programmed it to.
Does anyone have a link to the thread about the resistor?
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Report this Post01-03-2014 12:43 AM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 87FieroSport:

Confirmed:

My o2 sensor bounces back and forth (between 100-900mv.)
My INT and BLM seems to stay in the 140's consistently. Sometimes 120, then to 139-140.
My INT and BLM were between 128-144 (Jumped together at the same time from 120-142 a few times. Max 146 I think. (INT was 146 too.)
Coolant temp never rose above 200.

This is all under load between 35-50MPH.


With the INT and BLM that high, your ECM is adding more fuel than "normal". It thinks the engine is running lean.

That may be a function of the air temp. If the intake air temp is very cold, the ECM will tend add fuel to compensate.
It would be worth rechecking when the ambient temp is warmer, to see if the BLM and INT drop closer to 128.


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Report this Post01-03-2014 01:38 AM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have this issue in my Fiero, however I'm not sure in my case it's the tach because when I swapped out the tach with a supposedly working one from a member on here, it still read high by about 30% or so (same amount as before). Tach is pegged by about 4500 or so true rpm so it's hard to tell when I'm hitting 7k lol. The car has had this issue since I've owned it with a stock 2.8 then with a swap. Is there anywhere particular that the wiring might be causing this?
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Report this Post01-03-2014 09:47 AM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
If I was able to play my logs this would be easier..

I'll do an overnight cold start, key on/engine off data acquisition starting.
My engine does not warm up at all (only if I'm driving, it reaches only 180-200 and fluctuates. In park it can take up to 10-15mins)
I'll get the blm/int from cold start and warm start
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Report this Post01-03-2014 12:24 PM Click Here to See the Profile for gmctyphoon1992Click Here to Email gmctyphoon1992Send a Private Message to gmctyphoon1992Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by lou_dias:

Does anyone have a link to the thread about the resistor?


http://www.fieros.de/en/articles/tach.html
http://www.chalnet.net/Fier...tach/file%5B1%5D.pdf

 
quote
Originally posted by bcampbell:

I have this issue in my Fiero, however I'm not sure in my case it's the tach because when I swapped out the tach with a supposedly working one from a member on here, it still read high by about 30% or so (same amount as before). Tach is pegged by about 4500 or so true rpm so it's hard to tell when I'm hitting 7k lol. The car has had this issue since I've owned it with a stock 2.8 then with a swap. Is there anywhere particular that the wiring might be causing this?


I had the same problem where my tachometer read off than I replaced it with a known good one and that one began to read off too.. Sometimes the known good one can also go bad leaving you with two bad tachometers.. Im sure many members as well as I have a few bad tachometers that were once known good replacements to bad ones.. as far as the wiring it seems to be more that that the tach A) has a bad resistor and is just reading off.. the link above can fix it. or B) does not have the right resistor to read the correct engine RPM for you swap motor due to the problems you say you have which leads more to the tach. could be wrong though

------------------
1988 Pontiac Fiero Gt (fully optioned, factory leather, 5-speed, CJB T-Tops: Black w/ gray interior and blk wheels)
1992 GMC Typhoon #0203
1971Chevorlet Corvette 454cu/ LS5/ 4-speed/ convertible
1993 BMW 850 Ci 6-speed V-12

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87FieroSport
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Report this Post01-03-2014 06:09 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
Afrter aprox 15min in park (Before work.)

BLM 120
INT 120
TPS 1.02V

While cruising;

BLM 120 then hits 144 and drops to 120, then back to 144 a few times
INT 120 then hits 144 and drops to 120, then back to 144 a few times

Closed loop occurrs after 4mins.

I'm not seeing much wrong..
Could there be another cause for my horrible mileage?
If it was possible to let someone see my data, if they knew more that would help.


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Report this Post01-03-2014 06:15 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
Could my MAP be off?
I show 35-45 while in park/warming up.

I show 60 on my MAP when I go to hit the gas.
45-65 on my MAP through TunerPro while 40-50MPH fluctuating
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Arns85GT
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Report this Post01-03-2014 08:45 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Tach filter classic sign
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Report this Post01-04-2014 03:53 AM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gmctyphoon1992:


I had the same problem where my tachometer read off than I replaced it with a known good one and that one began to read off too.. Sometimes the known good one can also go bad leaving you with two bad tachometers.. Im sure many members as well as I have a few bad tachometers that were once known good replacements to bad ones.. as far as the wiring it seems to be more that that the tach A) has a bad resistor and is just reading off.. the link above can fix it. or B) does not have the right resistor to read the correct engine RPM for you swap motor due to the problems you say you have which leads more to the tach. could be wrong though




Yes it's possible that the new one has gone bad as well however I think it would be a strange coincidence that the tach reads off by exactly the same amount as with the old tach. I do have the correct tach as I have a V6 car, V6 tach, and V6 engine. Tach filter is not used with the engine swap so that's not an issue. And it's more than just being a few hundred rpm off as with lou's car. It more seems to be consistently off by a percentage not a set amount of rpm. With the ignition at run/engine off the tach sits at zero.
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Report this Post01-04-2014 08:19 AM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Your v6 Tach and v6 engine take a tach filter, period. Do get a tach filter and install it

Arn
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Report this Post01-04-2014 09:05 AM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Arns85GT:

Your v6 Tach and v6 engine take a tach filter, period. Do get a tach filter and install it

Arn


I've never seen a car with DIS that uses a tach filter.
Edit: 4 cyl Fieros with DIS don't use a tach filter either. My Fiero had one originally but when the DIS module was wired in it was deleted.

[This message has been edited by bcampbell (edited 01-04-2014).]

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Report this Post01-04-2014 11:02 AM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
The ignition isn't feeding the tach. It is the pulses going to the sparks. That tach needs the filter. The ignition does not.

Arn

[This message has been edited by Arns85GT (edited 01-04-2014).]

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Report this Post01-04-2014 05:45 PM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Arns85GT:

The ignition isn't feeding the tach. It is the pulses going to the sparks. That tach needs the filter. The ignition does not.

Arn



The tach signal is a 3x signal generated by the ICM. It is similar/the same as the signal sent to the ECM. It is my understanding that HEI distributors need a filter because the moving parts in the system cause interference. Since the only moving part in a DIS system is the crank trigger wheel itself, no external filter is required. Show me a car that came factory with GM DIS and a tach filter and then I may see a point in installing one.

It is also my understanding that a bad tach filter causes a jumpy tach vs. one which just reads high. This is not the case with my tach.

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87FieroSport
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Report this Post01-04-2014 09:30 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
I know I need a tach filter now. Okay.
But what about my poor mileage, any of the posted data resulting in that?

I'm not worried about my tach.
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Report this Post01-05-2014 03:54 AM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 87FieroSport:

I know I need a tach filter now. Okay.
But what about my poor mileage, any of the posted data resulting in that?

I'm not worried about my tach.


Your MAP sensor values sound reasonably normal to me, however the fact that the BLMs are jumping between 120 and 140 tell me that something is wrong. When the BLMs go to 140 the computer is adding fuel to compensate for it sensing a lean condition. Either there is a fuel system issue causing the engine to run lean or there is something wrong with the O2 sensor. When BLMs go to 120 it should actually be helping fuel economy as it's reducing fuel to compensate for what it senses as a rich condition. If you're running rich you could have a leaky injector or possibly other issues.
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Report this Post01-05-2014 09:35 PM Click Here to See the Profile for DooberSend a Private Message to DooberEdit/Delete MessageReply w/QuoteDirect Link to This Post
Filter was there to filter out RFI from the ignition system, doesn't make much of a difference nowadays... I run no filter in my '78 Malibu that originally had a filter, no issues.
http://www.youtube.com/watc...J5wZSaWNqPym1V7D91Sg

I'm still with a failing tach.
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Report this Post01-05-2014 09:57 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've noticed it goes to 140 only under acceleration.
Never does it go to 140 or above 128 during idle conditions.
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Report this Post01-05-2014 11:54 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I was working on the same problem but just decided to park it and take things apart and fix that and the other thing. Mine smells filthy rich, I changed my plugs and my gap .52 might be helping but it was pretty rich at .3 ( that's what they were).

You said it never warms up which mine did not either, that is to turn on the rad fan 195 (I think is the CTS I installed) and a 180 thermostat). Kinda cold that day and not driven.

Is your intake air sensor (IAT) and the ECM temperature sending unit indicating the proper temperature. Is your radiator fan or inside blower motor running? In TP they are shown in Celcuis at least when I have used it. My next step is to disconnect the cold start injector but I may run the TP first to see if anything shows up. I think I have to drive it and not just let it idle for good readings.
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Report this Post01-06-2014 12:53 AM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a CAI, with the IAT into it.
My mileage was the same before and after the CAI was installed.

My temp gauge reads a little above 190 if not 190 on my cluster (Same as TP.)

My radiator switch is broken actually come to think of it. My car used to overheat (Doesn't anymore since I did a coupe bumper swap.)
My CSI is deleted and plugged.

Does anyone know what the vacuum pressure of the Fiero is at idle? Maybe I have a leak? But my Idle in Park RPM shows 925 lowest, 1025 highest. on TunerPro

How would I be able to tell a leaky injector? Would timing affect my MPG? (I replaced my rear head, but never used a timing gun to achieve perfect 10degree timing. (it still idles fine.. it does feel a little hesitant at times, not very often.))
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87FieroSport
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Report this Post01-06-2014 12:54 AM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post

87FieroSport

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My TPS also reads 1.0v in Park. Is this allowable?
I know the TPS can have different tolerances, but I've heard .55 is superb.
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Doober
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Report this Post01-06-2014 02:29 AM Click Here to See the Profile for DooberSend a Private Message to DooberEdit/Delete MessageReply w/QuoteDirect Link to This Post
I believe you're around .5v high on the TPS (read of .5v at closed/idle on other vehicles) but I'd consult the factory service manual to be sure.
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bcampbell
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Report this Post01-06-2014 03:03 AM Click Here to See the Profile for bcampbellClick Here to Email bcampbellSend a Private Message to bcampbellEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 87FieroSport:

My TPS also reads 1.0v in Park. Is this allowable?
I know the TPS can have different tolerances, but I've heard .55 is superb.


1v sounds high; you can try resetting it by turning key to on/engine off with the TPS unplugged, then plug it in and start the car. It won't be a permanent fix but it should at least temporarily reset the TPS to 0.
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lou_dias
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Report this Post01-06-2014 10:24 AM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
Try readjusting your TV cable.
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87FieroSport
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Report this Post01-06-2014 06:21 PM Click Here to See the Profile for 87FieroSportSend a Private Message to 87FieroSportEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'll have to adjust it on a day off.
New job, 6 days a week so I'm only free to work on this whenthe dealer is closed.

I think I have it set right.. I replaced my TV Cable; but it didn't fix muc (would high idle)
Then I replaced my Throttle cable (much bettaaaah )

I'll set my TV again; need to find the procedure for this.

I learned it should be .5-.55v from you Lou;
I'll try to reset it or even replace it, would this cause my poor MPG or have an affect on it?
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Report this Post01-07-2014 12:54 AM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
My formula 5 speed averages 26mpg of mostly highway. A 3 speed auto will be worse. I don't think that would affect your mileage much unless you spend a lot of time idling.
The holes that hold the TPS in place should be slotted so adjusting the idle voltage is just a matter of twisting it and tightening it down.

Disconnect the TV cable and check your voltage with the key in the on position. That should tell you if it's tugging on it a little if you can't adjust the TPS anymore.

You adjust the cable as follows. Underneath the cable end (at the TB bracket )is a lever. You press the lever in and at the same time push the cable stub all the way in. You then rotate the throttle all the way open. The cable self adjusts.

[This message has been edited by lou_dias (edited 01-07-2014).]

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