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Almost stalls on takeoff. by AL87
Started on: 12-11-2012 06:29 PM
Replies: 20 (499 views)
Last post by: AL87 on 11-15-2013 04:30 PM
AL87
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Report this Post12-11-2012 06:29 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
Stock 2.8V6

when applying any amount of throttle from takeoff, the car almost stalls out, but then somehow it "hits" and goes.

thinking tps.
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Dodgerunner
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Report this Post12-11-2012 06:58 PM Click Here to See the Profile for DodgerunnerClick Here to visit Dodgerunner's HomePageClick Here to Email DodgerunnerSend a Private Message to DodgerunnerEdit/Delete MessageReply w/QuoteDirect Link to This Post
First test I would do is verify fuel pressure and leak down test.
You can also put a volt meter on the TPS and slowly move it and see if you see a voltage jump. MAP could also cause an issue.
Could be tps or could be engine going lean on fuel until the ecm starts correcting.
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ElTee
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Report this Post12-11-2012 08:00 PM Click Here to See the Profile for ElTeeClick Here to Email ElTeeSend a Private Message to ElTeeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Full power and lower the nose...

Who gets it?
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34blazer660
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Report this Post12-11-2012 08:18 PM Click Here to See the Profile for 34blazer660Click Here to Email 34blazer660Send a Private Message to 34blazer660Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ElTee:

Full power and lower the nose...

Who gets it?


you mean, "AOA stall, push up power!"


i would suggest checking TPS voltage
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AL87
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Report this Post12-12-2012 10:17 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
what should I be reading when I test the tps with a voltmeter?

any other way to test it? like disconnecting the connector? or is that with the iac?
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ElTee
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Report this Post12-12-2012 10:38 AM Click Here to See the Profile for ElTeeClick Here to Email ElTeeSend a Private Message to ElTeeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Im not sure what voltage you should be looking for, but with what you're describing, you'd be looking for a non-linear, or step change in the voltage. When you're moving the TPS around, it should be a natural progression from full closed to full open.

If you're reading (CAUTION: MADE UP NUMBERS!) 1v at closed and you move it around and it stays at 1v and then half way through the travel it jumps to 10v without a steady increase (1, 2, 3, 4...) then the engine could be getting faulty Throttle position info from the TPS and not doing the magic that the computers do properly.

as far as actually doing this procedure, I would leave it on the car and just press/pull on the throttle cable to make it move around.

[This message has been edited by ElTee (edited 12-12-2012).]

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Dodgerunner
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Report this Post12-12-2012 10:50 AM Click Here to See the Profile for DodgerunnerClick Here to visit Dodgerunner's HomePageClick Here to Email DodgerunnerSend a Private Message to DodgerunnerEdit/Delete MessageReply w/QuoteDirect Link to This Post
Might look at this post down a pic or two. http://www.fiero.nl/forum/A...100421-2-081601.html

You looking for a smooth increase in voltage from around .5 to 5 volts. Harder to see with a digital meter. Analog meters make it easier to see a jump or twitch.

[This message has been edited by Dodgerunner (edited 12-12-2012).]

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AL87
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Report this Post12-15-2012 04:51 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
also, I forgot to mention, when I disconnect the tps sensor there is almost a better response.
same with the iac.

is the car supposed to stall?
also, the map does this as well without stalling...
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AL87
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Report this Post12-19-2012 06:38 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
I just swapped in a known working tips and the car is still doing it.

Ignition?

[This message has been edited by AL87 (edited 12-21-2012).]

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AL87
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Report this Post01-01-2013 03:56 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
idk whats going on here still.

the tps isnt the problem. Ive swapped ones over from perfectly working fieros and it still does it.

it didnt do this until after I swapped in a reconditioned fuel rail and injectors. which were working fine before I pulled them off another car.

possible vacum, leak? <no codes though.
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Pete Matos
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Report this Post01-01-2013 12:15 PM Click Here to See the Profile for Pete MatosSend a Private Message to Pete MatosEdit/Delete MessageReply w/QuoteDirect Link to This Post
Al,
I know this is pretty obvious but if the car was running properly BEFORE you replaced the parts and now it is not then you either have some issue with the replaced parts or you managed to create a vacuum leak or some other issue when you did the swap. Sometimes I take a can of carb and choke cleaner and spray it without the little tiny hose around the intake to find vacuum leaks. If your engine changes sound or idle when you spray it around the intake and throttle body area it can help you find vaccum leaks that way. It is also easy to screw up the O-rings on the injectors when you remove and install them, you might try taking the UIM back off and poking around under there looking for hoses disconnected. Also make sure all the electrical plugs are firmly seated in the throttle body etc... It is real easy to miss things when you take that upper end apart. The other possibility is that a vacuum line cracked when you put the UIM back on. When I first got my 85GT here I pulled the UIM off and found the vacuum hose to the fuel rail was disconnected. I STILL have a running issue with this engine I cannot find thus far but I am working on it. Good luck finding your problem. Sometimes also having someone else look at all the lines and hoses they may see something you are missing. Check your EGR tube hookup too... peace

Pete
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Bruce
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Report this Post01-01-2013 12:20 PM Click Here to See the Profile for BruceClick Here to Email BruceSend a Private Message to BruceEdit/Delete MessageReply w/QuoteDirect Link to This Post
I replaced every known sensor and component, only to discover that the problem was several vacuum leaks in the many pipes under the plenum. I would check that first, since it seems to be one of the most common Fiero problems.
$.02, please.
Happy New Year!
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Phirewire
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Report this Post01-01-2013 09:06 PM Click Here to See the Profile for PhirewireClick Here to Email PhirewireSend a Private Message to PhirewireEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check your Alt output, my alt was going and it would get enough juice on heavy throttle to make it jump the battery.
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bobace455
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Report this Post01-02-2013 01:16 AM Click Here to See the Profile for bobace455Send a Private Message to bobace455Edit/Delete MessageReply w/QuoteDirect Link to This Post
Re-time the ignition, with the proper ports on the diagnostic plug jumped. (A and B I think?) I just jump em with a paper clip. My 86 2.5 did this and it was because the timing was too retarded. It took a second for the ecm to figure out what the issue was and then it corrected it causing the power surge. Just an idea! goodluck and keep us posted.
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AL87
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Report this Post01-02-2013 01:26 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
I will see here soon, I have to do alot of work coming up here.

I have to replace the exhaust gaskets.
replace/delete the muffler.
replace the transmission and motor mounts.
replace the CV axles.
and check this problem with almost stalling on takeoff.

[This message has been edited by AL87 (edited 01-02-2013).]

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AL87
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Report this Post11-13-2013 11:48 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
everything is fixed exept for this, no matter what I do with the tps, regardless of if its a new or used one, there is still no change, the rpm drops to almost stalling, and therein lies the issue, I don't want the car to stall when I want to just take off. no matter what adjustment.

the only thing I saw with a new tps is when I adjusted it to where it wasn't making contact with the finger linked to the butterfly, it threw a low voltage code. otherwise when I would bring it back to the "normal looking" adjustment, it still lagged on ANY throttle input...

the idle is around 1100-1200 at operating temp, and in gear (a/t)
I checked the vac lines for obstruction and leaks, and I sealed it all and made sure it wasn't a vac leak.

I still didn't read the voltage on the tps... I'll do that next, but I think its something else...
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AL87
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Report this Post11-14-2013 01:22 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
im running with the new tps now, at the factory setting. when I apply throttle input, steadily increasing it from a stop, no problem, maybe a slight dip in rpm (maybe 250ish) for a hair of a second and then it recovers and takes off.

however, if I stomp the throttle to wide open from a stop, the engine drops to 500 from 1100-1200 and then stalls out.

I can take off without a problem if the idle is higher than normal (1.25-1.5k area)

could the cam I put in make this issue more prominent with the retarded stock ecm?

[This message has been edited by AL87 (edited 11-14-2013).]

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AL87
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Report this Post11-14-2013 11:43 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
any thoughts?
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kikinz24
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Report this Post11-15-2013 06:56 AM Click Here to See the Profile for kikinz24Click Here to Email kikinz24Send a Private Message to kikinz24Edit/Delete MessageReply w/QuoteDirect Link to This Post
Check all your vac lines. Esp the pcv valve. If you have a decent sized leak it would definilty do that. Also hows the cap rotor and plugs a weak spark could cause ths car to dump too much fuel before the spark. ..
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Report this Post11-15-2013 08:45 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
Weak coil maybe?
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AL87
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Report this Post11-15-2013 04:30 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
im running an msd 6A series ignition control, spark is awesome.

the tps has something to do with it.
I don't know why the rpms want to drop off with the good tps, every time I give throttle input.

I put my original one on and bent the tab to where theres a two-penny thick gap between the throttle body finger and the tps' swing arm. and the car's throttle response is CRISP. but I've sacrificed the instant fire up on a cold start.

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