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Discussion Starter · #1 · (Edited)
So, back again with multiple cylinder misfires. Replaced the coil(still original) and it fixed the misfires. Running like a champ again. After a couple days it started running rough again. CEL flashing while running down the road. Replaced the ICM(original one tested bad) but didn't fix it. Replaced the opti with one from The Partslady earlier this year. Just recently took it off again and it is clean and dry still(has the Mitsubishi sensor). Plugs only have 40K on them and look good. Plug wires are Taylor, I replaced 3 years ago. O2s have around 35K on them and they are AC Delco. Got another coil under warranty replacement but didn't solve the issue. Verified multiple times that wires are not crossed. Have not replaced the opti wire harness or vent hose(still original). I have run an entire medium size bottle of Lucas injection cleaner through it along with 93 octane gas so the injectors should be clean. Imp has 140K on it. She starts up just fine. Runs rough at idle and with throttle. CEL flashes at certain RPMs, solid every other time. What else can be going on? Opti harness taking a crap on me? Any other ideas?
 

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if CEL on then pull some codes.......
i would scan while it idles and see what is going on.... assuming obd2 ?

-ALF
 

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Discussion Starter · #3 ·
The codes that were in there were P0100, P0300 and P1351. The MAF code might be from before since I never had it cleared out. Yes, it is OBDII. Original 96 PCM. Sorry, forgot to add that. The guy I had pull the codes was not able to pull anything while it was running.
 

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I would go back to basics......
you need Air, Fuel, & Spark.
you fix P1351 and I think P0300 will go away... if unsure about P0100 clear everything and get a new scan when CEL lights up again.
I would start here http://autorepair.about.com/library/faqs/bl022h.htm .... maybe crank position sensor given up the ghost ?

1. what did mech say about Fuel Pressure ? should be in the low 40's
2. any vacuum leaks causing too much air to get in and screwing up the air/fuel mix ?
3. You need to rule things out, check Ohms on injectors, Volts from coil to make enough spark, etc...
4. if it runs crappy in open-loop before pcm is managing engine, you should be able to track this down.
-ALF out...
 

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Plugs are cheap. 40K is enough miles for one to crap out. Replace. Wires routed properly and both ends seated well? IAC clean? As said before - go back to basics.
 

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Discussion Starter · #6 ·
Is there a possibility that the Opti wire harness is causing this? I am running out of options except for sinking more damn money into this thing. I've already spent ~$1400 this year on it just keeping it running. I don't have anyone around locally that would really be able to help me with this. Going to the dealership is mostly a waste since they really don't know very much about the "older" stuff. I'm almost to the point of driving it like it is until I can figure out how to afford something else. Sell it off and let someone else spend the money on it.
 

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Is there a possibility that the Opti wire harness is causing this?
Remove both check valves and blow through them. Should be about same flow/effort 1 way and nothing the other way. 1 is a check valve/filter (closest to the opti) and the other is a check valve only (closest to intake manifold). Test hose lengths by blowing through them while placing finger over opposite end. Should be no air coming through. Replace hose w/ thick walled silicone or standard vacuum hose if original is dry rotted or leaking.

Have you checked your vacuum? Should be around 20 hg.
 

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Remove both check valves and blow through them. Should be about same flow/effort 1 way and nothing the other way. 1 is a check valve/filter (closest to the opti) and the other is a check valve only (closest to intake manifold). Test hose lengths by blowing through them while placing finger over opposite end. Should be no air coming through. Replace hose w/ thick walled silicone or standard vacuum hose if original is dry rotted or leaking.

Have you checked your vacuum? Should be around 20 hg.
He asked if the opti wire harness could cause this not the opti vent harness.

Yes it could if it's bad/loose/broken.

I'm at the same point..... tired of dumping $ into my car.
 

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My CEL flashing was cured when I pinched the fuel injector connectors a bit tighter. The jaws on the connector are known to kinda wear out and 'yawn' open and make a bad connection.

It was cheap and easy...

-KP
 

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Discussion Starter · #10 ·
Update. Had Autozone scan the ECM and the only codes stored were P0300 and P1351. The P1351 is an issue with the IC circuit running higher than 4.6 volts. Could be a failed ICM, shorted or open circuit, or poor ground through the ICM. As angelo stated below, there's a good chance fixing P1351 will make P0300 go away.

The new ICM was checked prior to installing on the engine. I hooked the original ICM up and the engine ran the exact same as the new ICM. (I've made sure that the thermal paste is not blocking the metal contact on the ICM mounting holes) It appears the ICM is not the issue. Since I've had 2 different coils on it, I know that isn't the issue.

Is there a possibility that I am missing a ground somewhere? The only ones I've messed with in a long time are the ones from the large wire bundle that are bolted to the right side of the coil bracket. I had to disturb them because of swapping coils. I don't see anywhere where a wire might be cut or smashed that could short the circuit.

CEL is flashing at times during idle and running rough the entire time. It's flashing almost constantly whenever the car is moving.
 

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A shorting/burned Crank Position Sensor harness would cause my CEL to flash as well. Especially when I made left turns.
 

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Probably...way low on my list right now, but I'm going to get the codes read (again) tomorrow.
 

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Did you get your car fixed ....? to the OP.
-ALF out...
 

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Discussion Starter · #15 · (Edited)
Did you get your car fixed ....? to the OP.
-ALF out...
Sorry about not getting back sooner about this. It did pop in my head the other day.

Well, it's mostly fixed. Took it to the dealer and was told about a few things to check. They found out that one wire(drivers side rear, cyl 7) had gotten too close to the exhaust manifold and burnt through the outside rubber covering. Not sure if that was causing any issue or not but I replaced it anyways. They replaced the plug in Cyl 2 and the misfires stopped. I didn't have stock plugs in so I ordered 2 new plugs, Cyl 2 & Cyl 7(just in case). The ICM was evidently not mounted tight enough on the bracket so jimmy rigged with a bolt/nut combo and it's tight now. Had the P0300 code erased but the P1351 code will not disappear. Had a guy @ Advance Auto try to clear it out 3 times but it kept coming back. The car has been starting up just fine and running really good, even considering the cold weather the past couple days(into the teens at night). Not sure what else would be causing the high current on the ignition circuit. The ICM was checked 3 times in a row so it's good. All the grounds are clean and tight. I was debating about taking it back to the dealer to see what they could run down. Any other ideas? :confused:
 

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Yes, the Opti-Spark Electrical Harness can definitely cause those type of symptoms. I had to replace mine a month or so ago, due to the weak locking tab breaking and the connector became slightly unseated in the socket, and causing intermittent contact. It looked like it was seated in there properly, but I was able to push it down about 1/8 - 1/4" while investigating a no start issue. Locking tab was partially broken and not holding onto the mounting tit properly.
 

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#7 plug wire is always a suspect with a miss fire, guess we thought you checked that already. Don't tell us you put Bosch plugs in it,,,that's another no-no, same with their O2's.
 

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#7 plug wire is always a suspect with a miss fire, guess we thought you checked that already. Don't tell us you put Bosch plugs in it,,,that's another no-no, same with their O2's.
WOuld have been my first guess to check .
 

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Discussion Starter · #19 ·
Nada on the Bosch plugs or O2 sensors. You guys can sleep a little better now. Any ideas regarding the high current on the ignition circuit issue(P1351)?
 
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