Engine Performance problem
1998 Chevy S-10 4 cyl Two Wheel Drive Manual
I just rebuilt a 2.2l in my employees car. Engine timing marks were on the nose and dialed in for #1 top dead. When we fired up the engine it acts like the timing is advanced a tooth as the motor shudders/shakes heavily while it runs. I know that the timing gears and chain were dead on at assembly. I also now that if the timing was retarded a tooth we would get popping and sputtering out the pipe. We have none of that. There is no mechanical noise when she run but the shudder is very pronounced. There is no distributor on this, instead there is a cam position sensor. Also the check engine light flashes red. I can not find anywhere to adjust the timing on this engine. I am a seasoned mech and it feels like the timing is roughly 15-20 degrees advanced. Its like the engines fires on the upstroke and the combustions tries to stop the upstroke of the pistons. Not enough to stop it from running tho. Can anyone tell me how to adjust the timing on this vehicle. I also got the plug wires running 1, 3, 4, 2 with #1 being closest to radiator. Thanks for any advice you can give.
According to Alldata: the reluctor wheel is an integral part of the crankshaft and the Crankshaft Position (CKP) sensor is mounted in a fixed position, timing adjustment is not adjustable.
What codes are listed in the computer? Maybe we can take a different angle on this.
I assume you have a scanner to read data, or no?
June, 12, 2008 AT 9:58 AM
I currently dont have a code reader. And it doesnt appear that the blinking check engine light is flashing and sequences. How do we proceed?
June, 12, 2008 AT 10:54 AM
The blinkng light is essentially damage being caused to the converter from a rich condition.
Codes would be quite helpful. Should get a reader.
Recheck that all connector plugs are back in to the sensors.
We need specs to work with.
Check the fuel pressure, injector pulse and vaccum.
June, 12, 2008 AT 2:52 PM
We will get a code scanner tonight and post the codes tomarrow morning. Thanks
June, 13, 2008 AT 11:12 AM
(plz note all cyl #'s referenced are by firing order)
engine codes on 2.2l are PO300. We have checked all plug wires and they are new and installed correctly. We have pulled the plugs and double checked the gap and all are good. #4 seems fuel wetted so we are going to replace it. But on this note when a timing light is used to test electrical flow through the #4 wire it shows its firing. We also noted that when the motor stops running a short quick flame exhausts through the throttle body. It isn't possible to have the timing 180 degrees out on this is there. If it had a distributor I would try it but needless to say it doesn't.
Update: we took the wet plug from #4 cyl and relocated to #2 cyl and it burns fine. The plug from #2 was placed in #4 and it is wet so we think it may either the wire or the ingition module. We are planning to swap #3 wire with #4 wire to see if the issue relocates to #3 cylinder. If it does then we have an issue with the wire. If the issue stays in #4 after the swap then we have an issue with the module. But it is funny that the wire shows current passing through it. Any thoughts at this point?
Update: We found that after swapping a few things around like plugs and wires the issue still remains on the (firing order) #4 cylinder which puts us at the ignition module. We are checking for good connector connection to module and a spark gap ground-jump test. Test for inductance doesn't measure current strength.
June, 14, 2008 AT 5:27 PM
I would check the spark on that cylinder and find out how its firing compared to one that seems to be working.
Try hooking up a pressure guage and killing fuel to one injector and note the pressure drop, then turning it back on and dropping it again.
Does the cylinder with the wet plug have excessive fuel drop?
If the ignition module was bad chances are you would have no spark.
June, 16, 2008 AT 7:56 AM
We pulled the plug on # 4 cyl (plz remember we are referencing firing order when talking cyl#) and the new plug was wet. We dried it and grounded it against the chassis and confirmed a nice hot fat spark. So weak spark was ruled out. We started the motor with the plug removed and it actually ran smoother but we noticed a heavy " puff" of mist every time the air forced out through the spark plug hole. This confirmed that we had an injector that was stuck in the open position all the time. It was dumping tons of fuel into the cyl 100% of the time fouling out that cylinder. We installed a new injector and it seems to have solved our problems. Thanks for all of your help.
June, 16, 2008 AT 5:34 PM
Glad to hear I have been of some help.
I thought it would be that since the plug had good spark and was still wet, thats why I asked about the excessive pressure drop on that one injector which would confirm my theory.
Glad to hear you have the problem figured out!
June, 19, 2008 AT 1:23 PM
Actually I spoke too soon. Based on feedback from a chevy " tech" we were " advised" it was a sticky injector but upon replacing it we found to still have the same issues after it ran for about 10 minutes. We contacted Chevy and we were instructed to take a light emitting diode test light and jump it across the power leads to the injector. Upon which we found that there was only power momentarily applied when the ignition key was being rotated. Once in the " run" position there was no power being applied or pulsed to the injector. We contacted Chevy and were directed to a factory rep whom told us that when this issue occurs, 99% of the time there is a fault in the ECU injector module. Even more intresting is the rarity that these units actually malfunction. Unfortunately it looks as if we need to replace the ECU. We plan to have it replaced this weekend and will update you as to whether this fixes the issue or not.
June, 19, 2008 AT 6:36 PM
I dont suggest you replace it as it will probably have to go througha relearn procedure.