1991 Zr-1 Stumbling off idle

[Enginerd101]

Originally Posted by 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?

Schrade - It seems to smooth out a bit in the 1,200-2,000 range. By abrupt, i was trying to convey that when you ease into the throttle as if there is a cracked egg under it and you don't want to crack it more it is pretty smooth. Stumbling starts by applying the throttle any more quickly than this i.e. - letting the clutch out and applying throttle to start rolling. I'm not talking about ripping off any 0-60 runs by any means.

CEL is corrected thanks to suggestions on here - folded pin on dis.

[Enginerd101]

Originally Posted by 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)?

Ha - I'll take one off your hands if you have one leveling the table in your shop. Thank you for the wealth of knowledge you provide on this forum.

[Schrade]

If slow gas pedal (as opposed to quick), reveals no irregularities, I have no ideas about the original issue - the stumble that you have...

[XfireZ51]

Enginerd,

If the car had 60k on it w original injectors, I would suggest changing the in-line fuel filter, if you haven't done so already, and then check the fuel pumps for a few things. 1) the plastic clamps connecting the hoses in the tank should be replaced, 2) change the pump "socks". Frankly, I'd swap out the pumps to Bosch rotaries while I was at it or the Suburban pumps if original. Also, you need to check fuel pressure under load so a setup like Paul's will help doing that.

[scottfab]

Originally Posted by Enginerd101

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

Glad you fixed it. Been there done that. Here is the first time I had heard of it. Don't feel like the Lone Ranger.
This post was made right after I had seen the same issue.

***********************************************
Date: Thu, 20 May 1999 14:48:16 -0500
Reply-To: paul.smith@AMD.COM
Sender: "ZR-1 Corvette enthusiast list." <ZR1NET@HOME.EASE.LSOFT.COM>
From: paul.smith@AMD.COM
Subject: Re: [ZR1] Plenum Removed
To: ZR1NET@HOME.EASE.LSOFT.COM
Content-Length: 3819
Status: RO
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Be very careful plugging in this connector with the 1/4" bolt. Do not force
it into the socket!!! You can bend the pins on the ignition module very
easily. I found a bent pin on one that I took apart recently.

It helps to have very small hands :-)

Paul Smith
'94 #207 Admiral Blue/Black KUL ZR1