ROUGH RUNNING - ZR-1 Net Registry Forums

Pat Cooke · 11-01-2013

Hi
My 1990 ZR1 has a fault which I am trying to identify.
The symptoms are:- it starts from cold and runs perfect, good miles per gallon, etc., when engine has been stopped for 15 mins it starts up running rough and the miles per gallon go down significantly, at tick over the fly wheel starts rattling. When left alone for 45 mins it starts up perfect. I have tried shorting the socket for the diagnostic and no codes appeared, I am thinking it is something to do with the oxygen sensor or a temperature sensor. I would appreciate any help.

Schrade · 11-01-2013

Welcome onto the boards there...

Maybe not necessary to start 2 threads on the topic.

Cold start doesn't tell much, and highway running doesn't either. WARMED up [Closed Loop] idle quality means more than anything IMO.

Rattling is likely the dual mass flywheel.

What makes you think O2's? Or Coolant Temp Sensor?

Do you have FSM for the car? And a multimeter?

Pat Cooke · 11-01-2013

Thanks for coming back to me.
Two postings was a mistake, I'm new here.
Yes, I think it is the dual mass fly wheel rattling.
I am not technical but happy to learn, what is IMO ?
Is FSM service manual ? I don't have multimeter but thinking of buying one.

Kevin · 11-01-2013

it takes a lot for the dual mass to rattle and 02 sensors won't do it. you could have failing injectors

Schrade · 11-01-2013

IMO = in my opinion...

FSM = Factory Shop Manual.

And a fuel pressure test, with leakdown time, is in order. How many miles on the car?

We Gone · 11-01-2013

Just a guess, could be a bad coil when hot.

gbrtng · 11-01-2013

Find a TECH 1 scanner so you can look at all the ECM inputs - this does sound like a failing coolant sensor, but better to be sure rather than throwing parts at it.

Pat Cooke · 11-01-2013

Quote:

Originally Posted by Kevin

it takes a lot for the dual mass to rattle and 02 sensors won't do it. you could have failing injectors

Thanks ! You could well be right.

Pat Cooke · 11-01-2013

Quote:

Originally Posted by We Gone

Just a guess, could be a bad coil when hot.

Thanks! I thought it was a coil and renewed them.

Kevin · 11-01-2013

Quote:

Originally Posted by Pat Cooke

Thanks ! You could well be right.

i should mention, I had bad o2 sensors on my car...last year I think it was, all it did was set a code but it wasn't running poorly and certainly didn't make the dual mass rattle. the dual mass will eat up a lot of vibration so having something rattle it takes quite a bit of vibration

11-01-2013	#1
Pat Cooke Join Date: Oct 2013 Location: England Posts: 35	ROUGH RUNNING Hi My 1990 ZR1 has a fault which I am trying to identify. The symptoms are:- it starts from cold and runs perfect, good miles per gallon, etc., when engine has been stopped for 15 mins it starts up running rough and the miles per gallon go down significantly, at tick over the fly wheel starts rattling. When left alone for 45 mins it starts up perfect. I have tried shorting the socket for the diagnostic and no codes appeared, I am thinking it is something to do with the oxygen sensor or a temperature sensor. I would appreciate any help.

11-01-2013	#2
Schrade Join Date: Dec 2012 Location: NC Posts: 1,783	Re: ROUGH RUNNING Welcome onto the boards there... Maybe not necessary to start 2 threads on the topic. Cold start doesn't tell much, and highway running doesn't either. WARMED up [Closed Loop] idle quality means more than anything IMO. Rattling is likely the dual mass flywheel. What makes you think O2's? Or Coolant Temp Sensor? Do you have FSM for the car? And a multimeter?

11-01-2013	#3
Pat Cooke Join Date: Oct 2013 Location: England Posts: 35	Re: ROUGH RUNNING Thanks for coming back to me. Two postings was a mistake, I'm new here. Yes, I think it is the dual mass fly wheel rattling. I am not technical but happy to learn, what is IMO ? Is FSM service manual ? I don't have multimeter but thinking of buying one.

11-01-2013	#4
Kevin Join Date: Jun 2005 Location: pittsburgh Posts: 4,624	Re: ROUGH RUNNING it takes a lot for the dual mass to rattle and 02 sensors won't do it. you could have failing injectors __________________ It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B"

11-01-2013	#5
Schrade Join Date: Dec 2012 Location: NC Posts: 1,783	Re: ROUGH RUNNING IMO = in my opinion... FSM = Factory Shop Manual. And a fuel pressure test, with leakdown time, is in order. How many miles on the car?

11-01-2013	#6
We Gone Join Date: Apr 2004 Location: Atlanta, GA Posts: 2,170	Re: ROUGH RUNNING Just a guess, could be a bad coil when hot. __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

11-01-2013	#7
gbrtng Join Date: Feb 2006 Location: San Antonio area Posts: 1,182	Re: ROUGH RUNNING Find a TECH 1 scanner so you can look at all the ECM inputs - this does sound like a failing coolant sensor, but better to be sure rather than throwing parts at it. __________________ “Buy the best example of what you want, and pay whatever it takes. That way, you cry only once.” ~ Bruce Meyer