Engine Missing

[c4zr1]

I need a little help. I have a 92 with 17,200 miles on it. I know I do not drive it enough. It developed a miss and the engine service light is staying on. The secondaries are not coming on. I have changed out the plugs and fuel filter. Did not help. I am not getting any codes. The engine is idling right at 500rpm. I did do a reverse vacuum check and the vacuum does not hold constant, it leaks back down slow, but the vacuum pump does not stay on all of the time. It comes on about every 15 seconds and stays on for about 5 seconds. I did notice plug #1 and #8 was pretty black, but not wet with fuel.
I wish there was someone close that I could take it too, but Dallas is 6hrs away. Does anyone know of a good ZR-1 mechanic in Oklahoma City? I am only 4 hrs away from there.
Any help would be appreciated.

[Pete]

I think Jerry Downy lives in Oklahoma don't know where in Oklahoma he's at Carlilse this weekend try him on Monday.

Jerry is good people.

You can contact him at www.jerrysgaskets.com

I would say spark plug wires or bad injector.
Pete

[Paul Workman]

My engine is missing so bad...I can't even find it in the car!! (Just kiddin...sorta. Actually the engine IS missing from the car at the "moment" [sigh])

What Pete says is where I'd look first as well. But, if you have an SES situation, the secondaries will not be commanded open by the ECM. And, there should be a code too; at least while the SES light is on.

You can have it scanned at many of the auto parts stores; many do it for free. Scanners are great diagnostic tools, however they don't always point to the problem; but sometimes to the result of a problem.

For example, a leaking or stuck open injector will not throw a code or invoke an SES light - directly. However, if excessive fuel forces the O2 sensor out of range, the scanner will pick it up instantly, and if the condition is sustained, the ECM will finally light the SES light - as long as the ECM is operating in CLOSED LOOP configuration.

It sounds like you have a slow leak in the secondary system's vacuum circuit as well. That might be another item on you list, but not the one causing the miss - the scanner will shed some light on the path.

Like Pete said, my suspicions too lie with the injectors at this point, and since you changed plugs with no affect, then possibly wiring. Try pulling one plug at a time while it is idling and see if you can detect which "holes" are not firing and let us know.

Gotta run!

P.

[c4zr1]

Update on the miss

I put in a set of NGK Iridium IX plugs. Put in some Lucas Injector cleaner ran about 3/4 tank of gas through the engine.
I did decide to take it to the local chevy dealer to let them run an engine analysis on the engine. Had an appointment at 8:30 yesterday morning. I never did hear anything from them so I went back at 5p.m. and ask the service adviser if I could have an update on my car. He told me that they have not been able to look at it. That did not set too good with me I certainly did not want to leave it overnight so I told him I would just take the car. When I got back home and in my driveway the engine service light went out. It seem to be hitting on all 8 cylinders. I decided to take it out for a spin. It did pretty good, the secondaries started to kick in. When pulling up to a stop the engine service light did come on a couple of times, but after I set there a couple of minutes letting it idle a little faster the light would go back out. I made it back home then without the service engine light coming back on.
3 hours later
I started the Z no engine service light. Great!
I put the Marc Haibeck chip back in. The engine was already running bad when I purchased the chip from Marc. I took that chip out and put the stock chip back in while trying to dianose the engine miss. I was hoping that might cure my problem.
I took the Z for a test drive.
It drives like a ZR-1 should now. The chip makes it even run better.
I think I had dirty injectors and eventually the Lucas Injector Cleaner cleared up the injector or injectors that was not working.
I feeeeel a whole lot better now.

Thanks to those that responded!
Don

[Paul Workman]

Originally Posted by c4zr1

Update on the miss

I put in a set of NGK Iridium IX plugs. Put in some Lucas Injector cleaner ran about 3/4 tank of gas through the engine.
I did decide to take it to the local chevy dealer to let them run an engine analysis on the engine. Had an appointment at 8:30 yesterday morning. I never did hear anything from them so I went back at 5p.m. and ask the service adviser if I could have an update on my car. He told me that they have not been able to look at it. That did not set too good with me I certainly did not want to leave it overnight so I told him I would just take the car. When I got back home and in my driveway the engine service light went out. It seem to be hitting on all 8 cylinders. I decided to take it out for a spin. It did pretty good, the secondaries started to kick in. When pulling up to a stop the engine service light did come on a couple of times, but after I set there a couple of minutes letting it idle a little faster the light would go back out. I made it back home then without the service engine light coming back on.
3 hours later
I started the Z no engine service light. Great!
I put the Marc Haibeck chip back in. The engine was already running bad when I purchased the chip from Marc. I took that chip out and put the stock chip back in while trying to dianose the engine miss. I was hoping that might cure my problem.
I took the Z for a test drive.
It drives like a ZR-1 should now. The chip makes it even run better.
I think I had dirty injectors and eventually the Lucas Injector Cleaner cleared up the injector or injectors that was not working.
I feeeeel a whole lot better now.

Thanks to those that responded!
Don

Ummmm....OK. A good WOT now and then does wonders too. But, I've had the same set of symptoms which turned out to be O2s. A free scan from AutoZone would tell us a lot.

Just a thought. Hope it continues to please!

P.

[c4zr1]

Well things have changed some. I took my car back out today and I and I am still getting an SES light on from time to time. It will start up sometimes with the light on and some when I start it the SES light is out. When the SES light comes on I can drive it for a few miles and the light may go off, but when I get to a stop light it will come back on.
Puzzled.
I went by the local Auto Zone and they said they only scannd vehicles 96 and above so I could not get the codes read.

[Pete]

Originally Posted by c4zr1

I went by the local Auto Zone and they said they only scannd vehicles 96 and above so I could not get the codes read.

Do the old paper clip trick.

Ground A & B terminals (2 top right terminals) on the ALDL plug turn ignition key to on position and count the SES light flashes,each code will flash 3 times.

Pete

[LGAFF]

They should sell OBD 1 ADapters to check the SES.....I bought mine at Wal MArt, they are only around $20.

[tf95ZR1]

Originally Posted by LGAFF

They should sell OBD 1 ADapters to check the SES.....I bought mine at Wal MArt, they are only around $20.

http://www.gordonkillebrew.com/pages/800740/index.htm

[c4zr1]

Here are the codes I think I got when I did the A B pin cross
Code #34: Manifold Absolute Pressure Sensor Circuit Low - High Vacuum.
Code #42: Electronic Spark Timing (EST) Circuit.
Code #44: Left Oxygen Sensor Circuit Lean.
Code #54: Fuel Pump Circuit (Low Voltage)
Here are the codes I think I got when I did the A G pin cross
1. C12 9. H72

Where do I go from here?