1991 Zr-1 Stumbling off idle

[Paul Workman]

Originally Posted by Schrade

I've been investigating this since Oct.

Marc H (an authority), says it's normal.

I like the DM approach, but I'm not sure what the OP is experiencing is that same as yours. His sounds more severe, and all the way from 1200 up to 2000 rpm...and throwing a DIS code is a "horse of a different color", i.e., not "normal".

[scottfab]

Originally Posted by Enginerd101

Thank you all for all of the suggestions. May have a lead - car threw the check engine light today. Looks to be a code 16 (grounded pins a to b and counted flashes). Started with code 12 3x and then code 16 3x, then back to code 12. All I can find on this code is ignition 3 fuse circuit open. All fuses in kick panel on passenger side are good. Anyone have experience with this code?

Be sure you're on page 6E3-A-38 for code 16.
It is easy to get skewed onto a wrong page in this FSM

[Dynomite]

Lets just post what Code 16 is.....I do not own an FSM

And post the FIX..........as well when we are at it.....just in case I get a Code 16

What does the FSM look like? May have one and not know it......Is there one for 1990 and 1991 (are there separate FSM by year)?

[XfireZ51]

If you pulled the DIS connector, make sure you didn't fold a pin on the ignition module.

[scottfab]

Originally Posted by XfireZ51

If you pulled the DIS connector, make sure you didn't fold a pin on the ignition module.

That's a good point. If he pulled the plenum and disconnected the DIS connectors maybe one did not get all the way on or bent a pin. I did that once.

[Schrade]

Where is OP anyway here?

If he had folded an IgMod pin over, wouldn't that have given him a 16 light right away? He didn't have it at first...

OR... is 16 only lit up in CL?

Irrespective of the 16 code, I'm willin' to wager lunch that he has EXACTLY the same problem, that Marc ID's as a normal glitch, BASED ON HOW HE DESCRIBES THE PROBLEM:

"It idles reasonably smooth..."

"stumble [coming] off [of] idle." .............. not the first time I ever heard of sagging coming off of idle, huh Franke!!!

"It almost seems like it is choking out when you give abrupt throttle from idle up to a little over 1,200 rpm." .............. I don't like the 'abrupt' descriptor...

"Above 2k it seems like it runs ok." ...................... and what about from 1,200 - 2,000 there OP - smooth in that range too - right?

[Franke]

Chuck,
To be honest, I think it may be a little different than your situation in that yours acts well until your slowly reach about 950 RPM if I remember right then starts RPM hunting until above about 1200 RPM or so.
What really bothers me here is he indicates a reman ECU and I've seen defective ones from the auto parts counters. I don't really believe they actually test all functions of the ECM on the simulator bench over all RPM, temp, MAP, TPS, IAT, IAC ranges etc, etc . I'd like to swap in a known good one to eliminate that possibility. I wonder if that is why the car was traded in?
Like others above stated, I think the code 16 was due in part to the plenum removal as it occurred right after that maintenance. Could even be a loose connection or dirt at the DIS.

[scottfab]

[QUOTE=Schrade;195389]Where is OP anyway here?

If he had folded an IgMod pin over, wouldn't that have given him a 16 light right away? He didn't have it at first...

OR... is 16 only lit up in CL?

...snip...
/QUOTE]

He probably is at that thing called "work"

If it were snapped all the way off sure but bent has a chance of making mechanically intermittent contact. And on that back one if the screw is not tightened who knows?
Hard to say. Results of traversing the troubleshooting tree for a #16 would seem to be prudent.

[Enginerd101]

Originally Posted by XfireZ51

If you pulled the DIS connector, make sure you didn't fold a pin on the ignition module.

Xfire - you were exactly right. Folded a pin on the DIS. No more check engine light.

[Dynomite]

Originally Posted by Enginerd101

Xfire - you were exactly right. Folded a pin on the DIS. No more check engine light.

Good for you and excellent information to remember there XfireZ51.....appreciate that....and that applies to all plugs having multiple pins

Some plugs actually get lose also having the original plastic tabs break off that are suppose to keep the plug together.

I like it when someone (XfireZ51) NAILS IT and in one little ole sentence.......