ROUGH RUNNING 3

[Pat Cooke]

Hi from England,
Re: my 1990 ZR1.
Time to get it out of the garage and have another go at solving my rough running problem.
The symptoms are; starts up, runs smooth with normal power, as long as I keep the engine running it runs normally, if I stop the engine for more than 10 minutes it starts up running rough when hot, as if it is missing, power is down and fuel consumption up. I have replaced full set of coils which made no difference. Over the winter I purchased some Red Devil OBD1 diagnosis software for my laptop. Diagnostic trouble codes were 65 'oxygen sensor right side rich' and also 53 system voltage high,'battery voltage error' or 'EGR problem' or 'personal automotive security system (PASS-Key) circuit'. I purchased a new oxygen sensor which I thought I would put on the right side, having considered further I am wondering whether the right side sensor is detecting the rich mixture which is being caused by a faulty sensor on the left side or something to do with the code 53. Has the ECM got a limp home mode
Does anybody have any further thoughts ?
Regards
Pat

[scottfab]

Hi from England,
Re: my 1990 ZR1.
Time to get it out of the garage and have another go at solving my rough running problem.
The symptoms are; starts up, runs smooth with normal power, as long as I keep the engine running it runs normally, if I stop the engine for more than 10 minutes it starts up running rough when hot, as if it is missing, power is down and fuel consumption up. I have replaced full set of coils which made no difference. Over the winter I purchased some Red Devil OBD1 diagnosis software for my laptop. Diagnostic trouble codes were 65 'oxygen sensor right side rich' and also 53 system voltage high,'battery voltage error' or 'EGR problem' or 'personal automotive security system (PASS-Key) circuit'. I purchased a new oxygen sensor which I thought I would put on the right side, having considered further I am wondering whether the right side sensor is detecting the rich mixture which is being caused by a faulty sensor on the left side or something to do with the code 53. Has the ECM got a limp home mode
Does anybody have any further thoughts ?
Regards
Pat

My guess would have been coils too. :mad:
Oh well. Consider a leaking injector on the right side.
Also check the little hose on the MAP sensor at the firewall is on ok
and not full of oil.
As you have the O2 sensor though, that is a starting point.
A quick test for leaking injector is to pull the plugs on the right side
and use a long pipe cleaner to reach down and check for fuel.
You can cycle the key on to get the fuel pressure up but not start it.

PS did you know you started two threads with the same title?
No big deal.

[Pat Cooke]

Scott,
Thanks for your thoughts, very helpful.
They are the original injectors so are suspect ?
I did not intend to start two treads,operator error.
Regards
Pat

[XfireZ51]

Scott,
Thanks for your thoughts, very helpful.
They are the original injectors so are suspect ?
I did not intend to start two treads,operator error.
Regards
Pat

If they are original 90 injectors, that would suggest at least a look at them. How about some more info on the car, mods, km, etc.

[A26B]

Most likely a bad fuel injector, especially if they are original. A rich RH O2 sensor reading indicates to a bad fuel injector on the right bank.

Check:

Fuel Pressure Leakdown
(1) Place a fuel pressure gauge on the fuel rail
(2) Key on, Engine off, observe & note fuel pressure reading.
(3) Turn key off, observe fuel pressure leak down rate (pressure at 1 min intervals)

Inspect Spark Plugs
(1) If hot, allow engine to cool down
(2) Remove each plug, observe color. Black/sooty is rich.

If you need assistance with the Fuel Pressure Leakdown results, just post them here in this thread. Not sure about plugs? take a picture of them and post here.

Ideally, you should replace all 16 injectors. Otherwise, you may be chasing this issue frequently until all are replaced.

Hope you get it resolved with little difficulty.

[Pat Cooke]

No mods, 22,000 miles. it was imported in 1990 and mainly stored, only 2,000 miles in first
10 years. Second owner took it to 18,750 miles, I bought it 2 years ago, It is red with black
upholstery and I love it !

[Pat Cooke]

Jerry,
Thanks for reply, I am going to take your advice.

[scottfab]

Pat,
Did you get time to do any work?
Just checking back.
If you need anything, let us know.

[LantanaTX]

I had a similar issue and it turned out to be two issues, bad injectors and one bad coil. Injectors in 90-92 are a big problem over here caused by Ethenol added to our fuel. Are they adding Ethonol over there? If so might be time for injectors. Any type of alcolhol will destroy your injectors. I replaced with FIC injectors. Here is a good read:

http://zr1specialist.com/HAT%20Web/articles/Fuel%20Injector%20Replacement.pdf

[Pat Cooke]

Scot,
My ZR1 is now running smooth after a short stop, I am expecting the symptom to reoccur but in no hurry change injectors as I am not planning a long trip for a few months.
Thanks for your interest.
Pat

[Pat Cooke]

I had a similar issue and it turned out to be two issues, bad injectors and one bad coil. Injectors in 90-92 are a big problem over here caused by Ethenol added to our fuel. Are they adding Ethonol over there? If so might be time for injectors. Any type of alcolhol will destroy your injectors. I replaced with FIC injectors. Here is a good read:

http://zr1specialist.com/HAT%20Web/articles/Fuel%20Injector%20Replacement.pdf

Thanks for comments and article, very helpful !

Pat

[XfireZ51]

My rough running now seems to be cured, I fitted reconditioned injectors and that did the
trick. Many thanks to all who advised. What a Motor !!!!
Pat

Tally Ho Pat!😄

[Pat Cooke]

My rough running is now cured, I changed the injectors for a reconditioned set
and that did the the trick. What a motor !!!
Many thanks to all who advised.
Pat