I am totally confused currently and need a little help.
I have a 1988 Fiero 4 cylinder that has no distributor.
For a few days it was sounding like popcorn when I left of the gas, but didn't push the clutch in. Before I could fully check the exhaust and intake manifolds it cleared up.
This week I noticed it is currently acting like a misfire. The tach does not drop but you can feel jerks while driving occasionally like its not firing all cylinders. Well tonight on the way home I caught the check engine light so I got my code reader out. Hooked it up and read 25. Look it up and its for v6 engine MAT. Ok maybe my code reader can't handle a 4 distributor less engine properly. Jumper pins and read via the engine light 12 and 25.
Is it is possible for the 4 cylinder to through a code 25? Anybody encounter this before?
Trying to locate my PDF version of my repair manual.
MAT sensor should be right on the throttle body for 87-88 DIS cars. I would check out ogres cave for four cylinder information it may help it personally sounds like a fuel delivery issue "popcorn" usually indicates unburnt fuel hitting the manifold and igniting running too rich because the sensor isint reading properly so its set the ecu on a base tune to keep the engine from running too lean
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Ok All DIS items passed what tests I could find and do at the store. Bought replacements items and working from cheapest to the most expensive swapping out.
The crank sensor seemed to help with some of the misfire, but not cure it 100%.
I haven't replaced the MAT yet as it has not tripped again since starting to work through the DIS diagnosis. I remember ordering one into the local store, but they never contacted me that it was in. Sadly they sent it back since I didn't pick it up in 2 days.
How are your spark plug wires? Bad ones will cause misfire. And if you have popping during deceleration, or backfire, check your injector for dripping just after shutting off the engine. That would be leaking O-rings.
How are your spark plug wires? Bad ones will cause misfire. And if you have popping during deceleration, or backfire, check your injector for dripping just after shutting off the engine. That would be leaking O-rings.
Spark plug wires about 2 years old, but in great shape. Swapped out plugs just to make sure they were not failing.
Hung 2 new coils, 1 ignition module, 1 crank sensor, and 4 new plugs. Was a little better, but never got back to normal.
Put a new MAP and MAT sensor tonight. Went for a drive and tripped the engine light in no time at all. Was running the worst yet. Went home and read the codes. Almost everything under sun listed. Including the 55 that I had 2 years ago. Guess the refurbished ECM has failed now. Need to locate my receipt as the ECM I purchased supposedly had a lifetime warranty
If the computer turns out to be the final fix then it will be time to fix the failed AC. I think I will do as much as a full conversion as possible.
Will update folks when I get the replacement computer.
Thanks. ECM failures are rare. If so please let us know.
Well the new ECM is hung and all error codes cleared. Even #55. Start the car does the normal warm up idle and sounded pretty good. Backed out the driveway, waited at the stop sign, and things seemed ok. Rounded the corner and she started to die. Gave a little more gas and she pulled out, but jerking like I don't know how to use a clutch. Pushed it to the floor and she didn't finish the rev up before cutting out. Turned the corner back home got to the garage and she died. Tripped a code. Got her back in the garage and found my code reader.
Diagnosing code 42 now. No other codes at this time. Glance through chart looks like I will be working with the new ECM and the new ignition module for the testing.
The fuel pump and filter were replaced 2 years ago.
During all this fun I took the pressure after the fuel filter and before the throttle body. It was approximately 10 psi while idling. I say approximately since the gauge was not designed for low end reading.
Update: 20140706 Started diagnostic circuit check and got some confusion along the way.
1988 Fiero Service Manual 6E2-A-6
This seems to cover everything. I have some missing wires which should be fine since I do not have those options on my car. Sadly I have some wires that do not match
W02 LT.BLU instead of DK.GRN/WHT - A/C REQUEST, need to confirm where this goes...
W04 BLK instead of GRY/BLK - CRUISE, need to confirm where this goes but no cruise so probably ok
W18 missing ORN/BLK - P/N Switch, but not automatic should be ok
B04 missing LT.GRN/BLK - FAN (H.D. COOL), but not HD cool that I am aware of
B18 missing WHT - CRUISE, but no cruise should be ok
B24 GRY/RED instead of LT.BLU/BLK - A/C SIGNAL FOR FAN, need to confirm where this goes...
Has anybody else noticed different colors used from what is listed in the service manual?
I did go ahead and finish the KEY "ON" testing and found a couple items I want to look closer at.
B03 A/C CLUTH RELAY - not B+, was 0.017mV or basically ground. It does have an extra note for "A/C, Fan Off". The fan was off and vent was selected. I need to confirm this...
B09 INGNITION REF.HI - not 4.6V
B20 MAP - 4.62V not 4.75V
B19 TPS - 0.728V not 0.6V
I was going to complete the ENG.RUN tests, but during warm up the car shut down. It refused to start after that. There are no codes currently. I really want to check B03 and B09 before backing up and tracking down the current no start condition.
While looking further into the code 42 issue a scan tool was recommended, but I only have a code reader. My code reader can be upgraded to scan mode with software and I just need to call support on a weekday to see how much this will set me back. Sadly no local shops have an OBD1 scanner to loan me.
This is taking longer than I want to get fixed, but with my limited time lately it was just the wrong time for a break down.
[This message has been edited by longplaypg (edited 07-06-2014).]
I started with the no start diagnosis. The fuel injector was spraying what I thought was weak. Noid light indicated power through the connector and nice blinking. New fuel injector is spraying now, but still a no start. I can spray some starter fluid in and it will start, but only runs until the start fluid burns off. Went ahead and put my light up spark plug tester in line. With a little starter fluid I could start the car and walk back to see a nice steady spark for each of the 4 plugs.
I am going back to my book to do a little reading. This car was a daily driver until a couple weeks ago. Then it has sat with a full tank of gas since the new computer.
Thoughts?
2014/07/27 07:37 PM CDT Ok revisited items and working with Chart A-3 on 6E2-A-15 Made it down to Check for:
Fouled Spark Plugs (new and work fine with a little gas or starter fluid down the TBI)
EGR Valve stuck open (seems to move a little dirty, not sure of my testing so going to order another to swap in)
Low Fuel Pressure (will go rent again)
I seen some folks talking about disconnecting and plugging the line to the EGR to bypass it. I am guessing you just leave the unit hooked up physically. If I do this shouldn't the car start since it is not controlled by the ECM?
20140730 06:24 AM Used some carb cleaner on the old EGR, but even with a bit of soaking it didn't seem to clean up to well. Reinstalled the old EGR for now. The fuel pressure was reading about 11 during start conditions. After a little of time the car did idle for a period of time even though it would not start on its own. I left the fuel pressure gauge on overnight and it dropped to 0. Sadly now it will not leave 0 even after a few key on/off combinations. I hear the fuel pump running at least. Today the new EGR should arrive and maybe I can complete a few more diagnosis tonight after work.
20140801 08:18 PM The fuel pressure gauge I rented is a bit flakey and not pushing the release valve consistently if left extended periods of time connected. The car ran for over 500 seconds according to scan tool at 11-12 PSI. Still will not start on its own needs a little starter fluid or gas down the TBI. Got the new EGR and will check plugs Saturday.
I am really starting to wonder about the fuel quality. Tossed some sea foam in to suck up water if there is some in the fuel.
I hate to toss on a new EGR if I question the fuel quality now after all of the tests performed up to this point and the bad parts I have replaced. It was kind of odd that part way through all of this I went from being to able start and run crappy to a state where it no longer starts on it own.
What do others think?
[This message has been edited by longplaypg (edited 08-01-2014).]
Yesterday I used a little gas down the TBI and got the car to start and idle. While mowing for the next hour and a half I stopped in occasionally to check the fuel pressure and confirm it was still running. It ran the whole time cycling on and off the coolant fan. I turned it off and tried to start it again, but it just wasn't enough. It was trying but couldn't get over the hump of an easier turn over to running.
I let it cool down for over an hour and tossed on the new EGR. I tried 4 times to start it with no luck. I released the pressure gauge back to 0. I did simple 2 sec on and 10 sec off with a check of where the pressure was at. Starting from 0 I was well past my normal 2 cycles where the car would start. By about 8 attempts I felt that was too many to reach 10 psi. Jacked up the car and removed the 2 year old fuel filter. Slapped a new one and lowered the car again. After 4 on/off cycles I was still not at 10 psi. I shorted the fuel pump and it climbed faster than the old fuel filter allowed. When it reached 10 i tried to start the car and still wont finish without some gas down the tbi.
Before i drop the fuel tank i plan to get a little help to confirm the fuel spray as i turn over. I hate to clamp the old flex line return, but its time to confirm my new pressure regulator is working correctly.
Starting from 0 how quickly should it rise to the 10 psi? I am under the impression 2 key cycles should do it.
Emptied all of the gas out of the tank and dumped in my other car to mix with fresh.
All right new fuel pump installed. The old one I am not certain is bad because the clamps on the short piece of hose inside the tank were loose. Just plastic clips that were loose and slid down. New pump has same plastic clips again so instead of clamping my weak hands I used a plier to get an additional tooth clipped.
Fresh 5 gallons dumped in.
First key cycle 0 - 9 psi Second key cycle 10 psi
Sadly the car is still not starting on its own. Run the starter a few seconds and can hear the fuel pump continue a few seconds after letting off the starter.
Fuel is spraying out of the new fuel injector...
Starter fluid allows it to start for a short period. If I feed it enough starter fluid it will probably reach a period where it can idle. I just feel the underlying problem is still there since I have to use the fluid to make it start.
What in the world is going on.... Suggestions?
battery
Battery tester set for 690cca like battery markings 13.07v 632cca good battery according to tester can't check charging with battery tester since car will not start on its own, will test later...
Jumper aldl terminal "b" to "a", does ses light flash code 12 yes and fan starts up front
does "scan" display ecm data yes (reading prom code and others)
Does engine start no see chart a-3
6e2-a-14 469 pdf
battery condition? above test indicates it is ok but will test again
engine cranking speed? 325 rpm is that enough? can't seem to find information on this, but sounds nice and fast to me
fuel quantity? 5 gallons of fresh gas and gas gauge indicates almost half a tank
engine cranks but won't run 6e2-a-15 470 pdf
ign "on" ses light on
install scan tool shows data (reading prom code and others)
tps at closed throttle over 2.5v 0.47 v (old unit new unit was higher at 0.76 v)
collent below -30c (-22f) scan indicates 127.4f so ok
rpm while cranking scan indicates 325 rpm...
probe fuel pump test term, ign off 10, ign on, bulb lights for 2 sec after on yes
crank eng chk spark on 1-2 or 3-4 1 sparks, 2 sparks, yes
disconnect injector, crank eng, does fuel spary from injector no
connect injector test light, crank eng, does light blink yes
reconnect injector, crank eng, fuel spray yes
check for:
fouled spark plugs? no millage on new spark plugs, gap correct, not extra wet
egr valve stuck open? brand new egr with gasket
Low fuel pressure? 10 psi while trying to start, visit chart a-7 for further diagnostic
I will go back and redo the fuel injection ecm connector identification table again on 6e2-a-6 or page 461 of the pdf I will recheck the battery I feel like I skipped something or else I got bad new parts that function enough to not trip a code, but not fully function correctly. I feel like the fuel air mixture is incorrect to actually start the car. Dumping a little gas or starter fluid down the TBI allows the car start and with a little extra I can reach a point where the car will idle on its own.
What am I missing?
[This message has been edited by longplaypg (edited 08-17-2014).]
Still not starting on its own and letting myself get distracted with 1 of the ECM connections.
I think I found some of the answers to my ECM wiring questions.
6E2-A-6 (page 461 pdf) The white and black connectors on this page do not match the ones on the pages below. Now if I swap the connector colors on the following page at least things start to match up. It also helps explain a few things I was questioning: (pg 461) - - (pg 978)
W2 DK GRN/WHT - - W2 LT BLU
W4 GRY/BLK - - W4 BLK
W14 BLK (does indicate my have tracer color) - - W14 BLK/RED
W18 ORN/BLK (missing) - - W18 ORN/BLK [only for automatics and this is manual should be fine]
(pg 461) - - (pg 979)
B4 LT.GRN/BLK (missing) - - B4 Not Used [should be fine since no H.D. cool seems only for V6 and this is 4]
B18 WHT - - B18 Not Used [cruise, but no cruise on this car]
B24 LT.BLU/BLK - - B24 GRY/RED
8A-20-5 (page 978 pdf) C1 BLK (I think it should WHT)
8A-20-6 (page 979 pdf) C2 WHT (I think it should BLK)
Now I still worry about the voltages here and just wondering if other folks had noticed this problem with the service manual?
I hope these voltages can still apply and need to look at why my B3 BLU is not B+.
Does the 88 throttle body have the fuel pressure regulator in it with the rubber diaphragm like 84 thru 86? If it does the diaphragm could have a hole or tear in it
Does the 88 throttle body have the fuel pressure regulator in it with the rubber diaphragm like 84 thru 86? If it does the diaphragm could have a hole or tear in it
Yes it does.
I put a new one part way through the diagnosis. I have a second new one in my TBI rebuild kit that I can swap in for a quick test.
