need help diagnosing why a 4g63t runs too rich

[DannyRozco]

can anyone please tell me what can make a 4g63t run rich, and when I say rich, I mean too rich to drive. after about 15 minutes of the engine running the engine will start to idle funny. and when i drive the car, If I come to an abrupt stop, the car will die unless I keep my foot on the gas pedal. On the smog machine My car puts out 10% CO. not good. I have new O2, coolant temp works fine, no codes, but I recently found out that my ecu's ground had a bad connection. so i was curious of whether or not my ecu could be bad from shorting out or something. my chilton book says that there is a code that says the ecu is bad, but everyone else I've talked to said that if my ecu was bad than it would say everything else was bad and not the ecu. could someone give me some pointers. HHHEEELLLLLLPPPPPPP!!!!!!!!!!!!

 

[I-luv-em-all]

still could be your 02 sensor, in order to trip that cel you have to be on the highway for like 30 min before the ecu will throw a code. check boost leaks as well. if you go to radio shack and buy a 12v electrical buzzer and hook it up to the mpi diagnostic you will hear a constant buzz sound if the ecu is reporting that their is a problem with itself, here check this out http://www.vfaq.com/mods/wayback/BradBauer/electrical/code.html

 

[steve]

The car doesn't usually run if the bad ECU code is being output. It only puts out a solid signal when the ECU is unable to boot up and if the ECU can't run code it can't run the car.

Danny, you don't list any mods. If you car totally stock?

Steve

 

[x camaro owner]

hmm a primitive microcontroler booting up. hmm may be he means by setting the burned i/o's? i am not quite sure i have wrote code for lots of micros, booting up hmm that takes less time than i can explain try the prefix nano. boot up micro thats new for me. resest yes boot up? if it isn't "booting up" you got major issues. a bad ground will through an offset voltage which can throw some sensor's off. but a lot of sensor on these imports use voltage dividers which will compensate for a bad ground to a certain extent. man those engineers were thinking better than american ones, no wonder why imports last longer. grounding is every thing

 

[DannyRozco]

Thank YOu, to all who submitted some answers for my problem. tomorow one of my friends who is like a young mechanical Genius is gonna check out somethings on my car tomorow but If anyone has any pointers for me to tell him to look at I'd apprecitate that. I have heard something about an injector resistor box. i don't know anything about it, but could there be problems lying in there that are making my car run rich? Any comments would be greatly appreciated. An NO my car has no mods. My car is completely stock except for an underdrive pulley. thank you again. And have a great day. Mine :thumbdown

 

[Alexvw]

What was the problem? My engine does the same.

 

[c2ypt1c]

What was the problem? My engine does the same.

You honestly expect to get an answer from a thread that hasn't been updated in 9 years?

 

[DSM1G90]

To answer a 9 yr old thread to AlexVW is that the o2 sensor goes weak and can't tell the ECU to map the fuel mixture correctly. Plus, tired ECU's can do this also.

 

[Alexvw]

I took my ECU apart and noticed a chip burnt in the middle by the large diode and capacitors. I am assuming this to be the issue, but I still need to check for intake/boost leaks because I can't set my idle below 1000 rpm with the BISS screw. TPS is adjusted, ignition timing is adjusted, it has a walbro 190 on a stock fpr, hoping it is not too much fuel pressure at the rail. I have another fpr laying around I might try to swap on. Apparently the 02 sensor is new according to PO but need to confirm this by watching voltage on an analog meter. ECT sensor resistance readings are off a bit, may try to install a new one to see if that helps. Also noticed that the IAT sensor has around 2000 ohms (pins 6 + 8) which is not good, may need a whole new MAF unit. If the ECU sees 2000 ohms on the IAT itll assume that the temp is in the negatives, which requires more fuel. However, the ECT is more priority over the IAT and I am unsure if this is the issue.

BTW it is a 1990 4g63T 6 bolt, with a 1990 ECU and 1991 harness, in a 1974 vw beetle.

 

[ThunderChild]

well... thats kewl as hell. pics of the car alex?

if you have burnt circuits, your ecu is probably in need or repair or replacement due to leaking capacitors. good time to step up to an eprom with ecmlink.

 

[lasershark]

I agree, post up some pictures!

 

[toddevo]

x3 for pics

 

[Alexvw]

Sorry guys, just looked at thread. Here is my thread http://www.dsmtuners.com/threads/4g63-in-1974-vw-beetle.485648/