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Car runs but runs poorly after crank position sensor and icm update


Danpatters583

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The numbers for the spark plug wires should be stamped on the coil pack near the screws that hold it to the ICM on the Magnavox system.

 

 

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The engine should run with the MAF disconnected. It is one of the ways to check it. Stalling on connect or disconnect while running is a possibility since ECM gets caught by surprise but it should run with no signal from the MAF so it will use base programming. We want to see if the engine runs better or worse with the MAF disconnected

Edited by 2seater
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6 hours ago, 2seater said:

The engine should run with the MAF disconnected. It is one of the ways to check it. Stalling on connect or disconnect while running is a possibility since ECM gets caught by surprise but it should run with no signal from the MAF so it will use base programming. We want to see if the engine runs better or worse with the MAF disconnected

It doesn't run at all. When it stalls I try restarting it and nothing. It just cranks. 

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13 minutes ago, Danpatters583 said:

It doesn't run at all. When it stalls I try restarting it and nothing. It just cranks. 

Interesting, although I don't know what it means? My car is in storage many miles away so I cannot try to duplicate that scenario. Perhaps one of our other lucky contributors could verify?? The ECM should be able to cover for a missing sensor signal, actually most of them, and it will still run. If the car only starts and runs with the MAF plugged it, what do the readings look like from it? Warm idle is usually somewhere in the 4-6gm/sec range increasing from there. The general maximum I see with stock vehicles is around 125gm/sec full throttle at a shift point. Those aren't hard numbers but just a sort of expected range.

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1 hour ago, 2seater said:

 

I apologize I miss read your last about that. I tried it again while running this time (insert face palm here) and no change minus the stumble whole connecting or disconnecting. I did look at the info from the mass air yesterday and while warming was at 5gm/sec in idle.

 

I also verified that the plug wires are indeed working (hooked an inline test light to each cylinder) to verify its making it to the spark plug and it pulses. Also verified again that the wires are in the correct spot. According to the info I have its correct that is. Correct me if I'm wrong the firing order is 1-6-5-4-3-2 with cylinders 1-5 on the front side and 2-6 on the back side? I attached a pic of the closest thing I could find (95 Riviera) to this car. I attached a picture of what im using for reference. 16068584817704729756414443107750.thumb.jpg.9203854533cd36feb256e97194b02519.jpg

 

I think I'm going to replace my o2 sensor regardless at this point since I already bought it and planned on replacing it anyway. I did notice that there is a collar around the base of the o2 sensor that I can spin by hand and I don't think it should.  

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Also is there a crankshaft relearn procedure? I have a manual but it appears to only cover up to 89. 

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To my knowledge there is no CPS relearn procedure like there is on some OBDII vehicles. As stated before, there is a relearn process the ECM goes through after the battery is disconnected for a while but no specific driving procedure that I'm aware of.

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Changing the O2 sensor is a good idea but I don't think it will fix the problem if the problem occurs when the engine is cold. The O2 sensor doesn't go into play until the ECM goes into closed loop operation. That doesn't happen on our 3800 until the engine temp reaches about 140-160 degrees. Don't remember exactly off the top of my head.

 

I'm still guessing that you have an ignition problem since changing the ICM and CPS parts is when your trouble started. With all the things the Reatta diagnostics can do, one thing it won't do is set a code for ignition problems most of the time like a OBDII system does.

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It looks like you are in Colorado. I would buy one more ignition module/coil pack this time from a local salvage yard. Go to www.car-part.com and enter 1991 Buick Reatta [or 1992 Pontiac Transport]. Either one will get you a number of yards with what you need for a cheap price.

 You have replaced all the usual suspects  and the one unit that fails [or partially fails] without warning is the coil pack/ignition module. Over the years that is the one part I always swap out first. As a matter of fact I have three extra units [one in the trunk of the car I am driving, one in a box for Texas, and one in the parts bin]. 

 I would try that again.

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Ronnie: I agree but I have it figured it would not hurt.

 

Dave's: i have 4. Lol and I took one out of my brothers buick. Same thing. I plug mine in my brothers and it works. All 4 work in my brothers buick

Edited by Danpatters583
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Sounds like we can put the ICM/Coil Pack issue to bed. What else are you able to switch to your brother's car to help isolate this issue? [What car does he have?]

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13 hours ago, 2seater said:

The engine should run with the MAF disconnected. It is one of the ways to check it. Stalling on connect or disconnect while running is a possibility since ECM gets caught by surprise but it should run with no signal from the MAF so it will use base programming. We want to see if the engine runs better or worse with the MAF disconnected

 

6 hours ago, Danpatters583 said:

It doesn't run at all. When it stalls I try restarting it and nothing. It just cranks. 

 

4 hours ago, Danpatters583 said:

I apologize I miss read your last about that. I tried it again while running this time (insert face palm here) and no change minus the stumble whole connecting or disconnecting.

I got to thinking about this so I went to out to the garage to see how disconnecting the MAF would effect how my engine runs.

 

I have a battery disconnect switch on my car.  I disconnected the MAF before closing the switch. When I turned the key, the engine fired right up and seemed to idle normally. I rived the engine several times and the engine seemed to respond normally. I didn't drive the car but I'm confident it would run smoothly on the highway but maybe not perfectly with the MAF disconnected. I've done this in the past. I did it again tonight just to confirm the results would be what I expected when starting from a cold start with the MAF unplugged. Of course the check engine light was on and a there was warning was on the CRT but that is normal when unplugging the MAF.

 

I don't know why your engine won't start with the MAF disconnected or what that means really. 2seater may have some ideas. He knows these engines inside and out.

 

From what you describe it seems like the engine isn't running on all cylinders.  Not sure where you should go from here. I assume you have checked the fuel pressure? This is getting to be a long thread and I've forgotten. If not you should.

 

Assuming fuel pressure is good, I believe my next step would be to get the engine running steady at about 1000 RPM (or whatever RPM it will run at) and then pull the plug wires off the coils one at a time, and then reconnect it, to see which one makes a change in the way the engine runs and which one doesn't.  If you find one (or more) that consistently don't seem to effect how the engine runs, that is where you should start your investigation and find out why that cylinder isn't running correctly..

 

 

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5 hours ago, Danpatters583 said:

I apologize I miss read your last about that. I tried it again while running this time (insert face palm here) and no change minus the stumble whole connecting or disconnecting. I did look at the info from the mass air yesterday and while warming was at 5gm/sec in idle.

 

I also verified that the plug wires are indeed working (hooked an inline test light to each cylinder) to verify its making it to the spark plug and it pulses. Also verified again that the wires are in the correct spot. According to the info I have its correct that is. Correct me if I'm wrong the firing order is 1-6-5-4-3-2 with cylinders 1-5 on the front side and 2-6 on the back side? I attached a pic of the closest thing I could find (95 Riviera) to this car. I attached a picture of what im using for reference. 16068584817704729756414443107750.thumb.jpg.9203854533cd36feb256e97194b02519.jpg

 

I think I'm going to replace my o2 sensor regardless at this point since I already bought it and planned on replacing it anyway. I did notice that there is a collar around the base of the o2 sensor that I can spin by hand and I don't think it should.  

I don't know why all firing orders start with #1, but I guess it is just convention. In any case, 6,5,4,3,2,1 makes it way easier to get the picture with the coils lined up in that diagram above, top to bottom 6,5,4, then back to top and 3,2,1. Good old waste spark in action. It doesn't even matter if the plug wires are switched around on each coil, as long as they stay on that coil. 

 

If the ring under the O2 is what you are talking about, that's the sealing gasket washer. If that is loose, I am surprised you haven't mentioned an exhaust leak? If that connection is leaking, it will draw raw air into the exhaust and play hob with the fuel mixture. Changing the O2 is never a bad idea, particularly if you don't know the history.

 

Way back in the beginning you mentioned the fuel filter was full of rust and crud. Have the injectors themselves ever been serviced? I mentioned earlier to check the electrical connections for the injectors are snapped in place if they have ever been disturbed. You can turn injectors on and off individually in the override section of the diagnostics which may help isolate a cylinder not performing up to par. The IAC will recover the idle speed so look/listen for momentary change in the idle as you switch them on and off.

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5 hours ago, 2seater said:

I don't know why all firing orders start with #1, but I guess it is just convention. In any case, 6,5,4,3,2,1 makes it way easier to get the picture with the coils lined up in that diagram above, top to bottom 6,5,4, then back to top and 3,2,1. Good old waste spark in action. It doesn't even matter if the plug wires are switched around on each coil, as long as they stay on that coil. 

 

If the ring under the O2 is what you are talking about, that's the sealing gasket washer. If that is loose, I am surprised you haven't mentioned an exhaust leak? If that connection is leaking, it will draw raw air into the exhaust and play hob with the fuel mixture. Changing the O2 is never a bad idea, particularly if you don't know the history.

 

Way back in the beginning you mentioned the fuel filter was full of rust and crud. Have the injectors themselves ever been serviced? I mentioned earlier to check the electrical connections for the injectors are snapped in place if they have ever been disturbed. You can turn injectors on and off individually in the override section of the diagnostics which may help isolate a cylinder not performing up to par. The IAC will recover the idle speed so look/listen for momentary change in the idle as you switch them on and off.

I will have to play with that. I will also have to play with what ronnie mentioned too. I also don't know why my car won't start with maf disconnected. But while running I get the same results as if it were plugged in. Regardless if it's plugged in or not. In the morning I was going to check all injectors for operation and all that and possibly do a compression test too. Just to rule any thing else out. 

 

There is no exhaust leak that I can tell coming from it. It's above the hex portion of the o2 sensor. Looks like part of the body of the sensor its self. 

 

I have not serviced the injectors. But literally all fuel components minus lines and injectors have been replaced/repaired. Fuel pressure at the rail is 40 lbs before starting. Once running in idle it sits right about 39 or so. I think I read some where that its supposed to be 40. +/- 2lbs. So I think that's good? But both of you read my mind. Im fairly certain my ignition system is up to par at this point. But I will pull wires off to confirm. I also rented a fuel injector noid light kit to check for signal to the injector and a stethoscope to listen to the injectors to see if they are firing. I'm tempted to pull the rail and injectors off and either buy new injectors or have them cleaned or something just to rule that out as a possibility. 

 

Also, the crank position sensor calls for a gap of .020. Between the outer reluctor ring and the sensor. Is this correct? I have it set to that currently. 

 

As of right now here is a sum of everything:

1. I have confirmed that the ICM and coils work

2. According to inline spark tester all wires appear to be delivering spark to the plugs. Light flashes consistently with no interruptions. So I'm assuming plug wires are good.

3. All sensors appear to be in working order and with in spec. according to the on board diagnostics.

4 fuel pressure at the rail is roughly 40lbs. 

5. All basic ignition components have been replaced with new. Ex. Plugs, wires, ICM, coils.

6. All fuel components minus injectors, fuel rail, and lines have been replaced or repaired. I blasted the lines leading up to the rails out with compressed air and some fuel system cleaner. 

7. Crank position sensor has been replaced. 

 

Hope this helps kind of sum up everything I've done. I know it's a long thread. I appreciate all your help.

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I agree if whatever moves on the O2 above the hex, won't cause a leak. It could be the metal shield I see around the wire on some brands which isn't unusual.

 

Design pressure for the fuel system is 3bar or 43.5psi. So key on, engine off, it normally is more than 40psi by some amount but of course gauge accuracy makes all measurements a relative reading, not an exact number. Fuel pressure should be reduced by about one psi for every two inches Hg of manifold vacuum with the engine running. Removing the vacuum connection on the fuel regulator should cause the fuel pressure to rise back to the base static pressure reading, something north of 40psi. Blipping the throttle should cause an instant increase in fuel pressure as well. The reason I mention all of this is there should be fairly substantial difference in fuel pressure between key on engine off and engine idling. My experience shows 16"-18"Hg of idle vacuum on my car, so fuel pressure is generally 36-37psi at warm idle. If you are at high altitude, the whole scale of pressure readings may be shifted lower, but I would still think the relative readings should follow the same trend? If there is little to no change in the fuel pressure with the vacuum connected and disconnected, engine idling, something is wrong with the pressure regulator or there is very low vacuum in that connection or actual manifold vacuum (a substantial leak somewhere)

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I FOUND THE PROBLEM!!!! I did what ronnie mentioned (can't believe I didn't think of it earlier) which was to pull each wire off until it doesn't make a difference to idle quality. So turns out, as a matter of coincidence, on cylinder 4 I had a bad spark plug wire so I swapped it with another set I bought from a 91. After I swapped the wire it started making a ticking sound. So I pulled the plug and found it was cracked down the insulator. I've never seen that before. I will attach a pic of the plug. On a side note if any one reading all this in the future is swapping over to the Delco ignition set up I HIGHLY recommend buying a spark plug wire set from a 91 reatta. They fit beautifully and make a nice solid connection. 

 

Thank you every one for your help! You guys are miracle workers! I learned so much about this car with your guy's help! I will admit my troubleshooting skills have certainly perished from not getting enough sleep due to working night shift and all your guy's help in steering me is greatly appreciated!

Message_1607025565841.jpg

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2 hours ago, Danpatters583 said:

I did what ronnie mentioned (can't believe I didn't think of it earlier) which was to pull each wire off until it doesn't make a difference to idle quality.

Sometimes getting down to basics and using old school troubleshooting pays off. Glad to hear you found the problem!

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I wonder how many other guys over the years had a bad plug and just kept looking at the "big" things? Glad you found the problem. And the best part is it was an easy "see" as #4 is on the front side of the engine.

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I've had a hairline crack in a plug insulator before.  My brother-in-law brought me his Mustang to tune it up back in the '70s.  He bought all new points, plug wires, filters and distributor cap at NAPA and the spark plugs at Walmart because they were on sale. I installed them and the little inline 6 cylinder engine ran like crap. I spent three of my evenings after work tracking down a spark plug with a hairline crack.  I used the same method of pulling plug wires off one at a time to find it. I might have cracked it someway myself installing the plugs but since then I have never even considered buying a spark plug from Walmart.

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