This is my daughter's car. 2.8L engine. The trouble started about a week ago when she said it got hot in traffic. It didn't overheat. I checked it later that day and neither radiator fan would come on. I unplugged the engine coolant temperature sensor and both fans came on. I replaced the ECT sensor with a spare but the fans still don't come on.
Since then, the car has started dying while driving. Last night it would crank but not start, until I pushed the gas pedal to the floor and even then it ran really rough for about 20 seconds then evened out and ran fine as I drove for a few miles. My plan was to have my daughter swing by a parts store to get the codes read but my daughter couldn't get it started.
The car has been in the family for a decade and had an engine rebuild 2 years ago. It's never had any of the sensors replaced. Ordinarily I'd suspect the crank position sensor was going bad, or maybe the ICM, but that wouldn't expaln the fan problem, would it?
[This message has been edited by Quad Raider (edited 08-15-2012).]
ecm itself? We had an 85 cavalier that the fans wouldnt come on did all sorts of test and all wiring and sensors where fine just was no longer getting a signal from the computer we just ran a switch. Maybe yours has a similar issue and the ecm failed.
I think I can. I'll try that tonight. I've found all kinds of theories on the internet about what the problem could be, from clogged fuel injectors to a dying fuel pump.
But nothing about the ECM or the fuel pump. I also noticed that the positive battery cable end at the battery had some corrosion on it. The O2 sensor may be factory original, so I think I'll start there first.
k.i.s.s. start by testing the FAN RELAY.. and fuse.. my bet is on fan relay.. start car (if you can) and put a/c on.. that would kick fans on, bypassing the sendor, but not the relay,, no fans, relay or wiring, fuse..
I think the fans and the relay are good, because the fans came on when I unplugged the ECT sensor. I will replace the crank position sensor this weekend. I also need to replace the positive battery cable.
Haven't had much time to work on it. I replaced the crank position sensor and it didn't make any difference. I also had the ICM checked and the parts store said it was good. Don't know that I believe it. My plan is to replace the ECT sensor with a new one this weekend.
MAP is a big thing, will make it run like crap. ECT is probably thrown because you unplugged it. remove the negative battery cable for 30 seconds - 1 minute, then put them back on. Try to run the car, then get codes again.
A Faulty MAP could possibly cause loads of issues, including no performance.
Does it fire up when cold, and die when hot? in 89 GM had some problems with the Multec fuel injectors. Ohm them out if you can, should be around 16 ohms. Have a 'Vette in the shop right now that has a fuel injector problem (Multecs) and it causes the ECM to stop running the injector drivers. No codes in that situation.
That's exactly what it's doing. It seems to run fine when it's cold, then gets worse as it warms up. Today I drove it to work and back (60 miles). At lunch I discovered the vacuum line had come loose from the MAP sensor. Didn't make much difference. Fuel usage was alarming and I trailed thick black smoke the whole way.
That's exactly what it's doing. It seems to run fine when it's cold, then gets worse as it warms up. Today I drove it to work and back (60 miles). At lunch I discovered the vacuum line had come loose from the MAP sensor. Didn't make much difference. Fuel usage was alarming and I trailed thick black smoke the whole way.
I would DEFINATELY check the resistance of the injectors. One shorted injector would cause the injector drivers to stop working after the engine got hot. A bad injector will also cause it to run a bit rough, maybe rich, etc etc.
Would a bad injector (or two or three) account for the huge fuel usage? My daughter was complaining of poor fuel economy for a week or two leading up to my discovering the fans weren't coming on. Is it possible at least one injector is stuck open, dumping a lot of fuel into the engine?
Would a bad injector (or two or three) account for the huge fuel usage? My daughter was complaining of poor fuel economy for a week or two leading up to my discovering the fans weren't coming on. Is it possible at least one injector is stuck open, dumping a lot of fuel into the engine?
That is a possibility!
I was wrong on my earlier resistance number, that's for an L98's injector. Find your engine code in this list, and here are the values for you to use for testing:
The injector for the #1 cylinder showed half the impedence of the other 5. I replaced it, and replaced some of the vacuum lines that appeared as though they'd melted. I put it all back together and it still does the same thing.
The guys over on the Quad4 forums seem to think at least one of the injectors is stuck open. They say that flooring the pedal shuts off the fuel flow, so if an injector or two is stuck open that would allow the engine to start instead of flooding.
Crank position sensor O2 sensor MAP sensor ECT sensor Temp gauge sensor Ambient air temp sensor #1 fuel injector
The car has 261,000 miles on it and all but one of the temp sensors was original.
I don't think the cat is clogged, but I'm on vacation next week and may cut it off and replace it with straight pipe because it's worn out.
The car runs well and starts easy when cold. When warm, it starts but runs a little rough but then smooths right out. The radiator fans still are not coming on, so I think the ECM is bad.
[This message has been edited by Quad Raider (edited 10-04-2012).]
Here's another update. I replaced the ECM and it didn't change anything, except that the digital tach now works, which is very nice. The car will start and run fine when it's cold. When it's warm, I have to ride the gas pedal a little bit to keep it running. After about 15 seconds it will accelerate to about 2700 rpm, then slow down and idle perfectly. Sometimes it will die when I come to a stop but will start right up again. The radiator fans still do not come on. Yesterday I disconnected the temperature switch and both fans came on. Must be a bad temperature switch, right?
[This message has been edited by Quad Raider (edited 01-20-2013).]
Still searching for the answer. Last week I discovered a coolant leak at the thermostat housing. One of the bolt holes was stripped, so I used a longer bolt to reach good threads to tighten it down. Could this be caused by air in the coolant system?
Final update. The car has gone to the big parking lot in the sky. I never did get the problem solved, though I was leaning toward the computer at the end. The temp gauge quit working and I had a minor leak in the radiator. Not a good combination and it overheated on me and blew the head gaskets again. I decided to take it to the recycler, instead of fixing the head gaskets, getting a new radiator, new tires and a new computer. At 272,000 miles, it had a good life.
Before the final blow happened I talked to a mechanic who said he believed a new computer would fix it. He said the salvage yard computer I put in it probably had the same issues as the original one it replaced.
