hard to start and chugging
09-10-2006, 08:45 AM
#1
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Car: 88 iroc-z
Engine: 5.7tpi
Transmission: auto
hard to start and chugging
can anyone help the car is an 88 5.7 TPI
it fires up straight away but stops immediately after 5 or 6 goes it keeps running sometimes with an erratic idle sometimes its fine
as for driving at times its fine or it can run good for 10-15 minutes then start chugging or it can run bad from start up
this has been going on for a couple of months but is getting worse and is now a daily occurence
in the time this has been happening it has given me a code 34 on 3 occasions
a code21 once a code 54 once
and all three on one occasion
I initially thought it was a fuel problem before the codes started coming up but the fuel pressure is 38psi at idle with the vacuum hose connected and that was when it was idling erraticaly, fuel flow rate is 3 litres per minute (0.8 gpm)
TPS is 0.59v with the throttle closed and 4.2v with it wide open
I have removed and cleaned every wiring connection I can find under the hood I did find some exposed wiring on the fuel pump relay which may explain the code54
distributor module was replaced 7k miles ago pick-up coil shows 800 ohms resistance
I have checked for vacuum leaks the IAC has been removed and cleaned
the injectors have been removed cleaned and tested 2.5k miles ago
I had it scanned and it was constantly switching between open and closed loop
I have replaced the ECU which made no difference
If I disconnect the plug from the MAF sensor the car runs smoothly and goes bad when I reconnect does this mean the MAF is faulty or have I just forced it into limp mode
Can anyone help I'm getting desperate
it fires up straight away but stops immediately after 5 or 6 goes it keeps running sometimes with an erratic idle sometimes its fine
as for driving at times its fine or it can run good for 10-15 minutes then start chugging or it can run bad from start up
this has been going on for a couple of months but is getting worse and is now a daily occurence
in the time this has been happening it has given me a code 34 on 3 occasions
a code21 once a code 54 once
and all three on one occasion
I initially thought it was a fuel problem before the codes started coming up but the fuel pressure is 38psi at idle with the vacuum hose connected and that was when it was idling erraticaly, fuel flow rate is 3 litres per minute (0.8 gpm)
TPS is 0.59v with the throttle closed and 4.2v with it wide open
I have removed and cleaned every wiring connection I can find under the hood I did find some exposed wiring on the fuel pump relay which may explain the code54
distributor module was replaced 7k miles ago pick-up coil shows 800 ohms resistance
I have checked for vacuum leaks the IAC has been removed and cleaned
the injectors have been removed cleaned and tested 2.5k miles ago
I had it scanned and it was constantly switching between open and closed loop
I have replaced the ECU which made no difference
If I disconnect the plug from the MAF sensor the car runs smoothly and goes bad when I reconnect does this mean the MAF is faulty or have I just forced it into limp mode
Can anyone help I'm getting desperate
09-10-2006, 12:29 PM
#2
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Car: 91 formula
Engine: 305
Transmission: t5
sounds like a problelm im having....
hows your voltage on your volt gauge doing ? i have a feeling after replacing all the sensors and it not helping that i have a bad battery beacuse it wont stay charging at a consistant voltage and if just the key is on and not running i only show like 9-10 volts on the guage
hows your voltage on your volt gauge doing ? i have a feeling after replacing all the sensors and it not helping that i have a bad battery beacuse it wont stay charging at a consistant voltage and if just the key is on and not running i only show like 9-10 volts on the guage
09-19-2006, 04:00 PM
#4
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Car: 91 Z-28
Engine: 360TPI
Transmission: PA Racing 700r4
Axle/Gears: 3:73
My car was having some of the same issues... I replaced the knock sensor, alternator, starter and battery; it seems to run better now and my timming was off 6 degrees so thats now adjusted... So.. So Far So Good wit my issues
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