Ignition module ground

[8upZR1]

I have had no success but I did notice that wheneve I try to start the motor the A/F gauge reads between lean and stoich. My mustang will only start when the mixture is rich. Has anybody taken a look at the A/F ratio on their ZR1 when the motor is cranking? A few months ago I asked all the various people who burn chips for the ZR1 if they could burn me a chip or two with different fuel settings for cranking and I was told by everyone that it was impossible, or that it would be easier and more cost effective to wire up a stand alone injection system. Does anybody know of a method to adjust fuel mixture on these cars without resorting to one of those Jap piggyback boxes?

[Tyler Townsley]

Originally Posted by 8upZR1

I have had no success but I did notice that wheneve I try to start the motor the A/F gauge reads between lean and stoich. My mustang will only start when the mixture is rich. Has anybody taken a look at the A/F ratio on their ZR1 when the motor is cranking? A few months ago I asked all the various people who burn chips for the ZR1 if they could burn me a chip or two with different fuel settings for cranking and I was told by everyone that it was impossible, or that it would be easier and more cost effective to wire up a stand alone injection system. Does anybody know of a method to adjust fuel mixture on these cars without resorting to one of those Jap piggyback
boxes?

The start enrichment calibration can be changed. No one has found a need to do it so they are not sure what to change and by how much without the car right there to see the result of thier efforts. If you have a lean start condition I would look at the primary injector function first.

The motor mounting in the zr1 is different than a normal 350 which is why they have a different cradle, that may be changable but it could not be used for the lt5.

If you review the testing procedures for the dis you will note the wornings about using a vtvm to check outputs. I assume this is because the additional loading will damage the internal cktry. Based of your results with the ISS I think the dis module or the crank sensor is bad, I think the MSD may have cause the dis to overheat and fail. On way would be to install your dis in another running car to see if it exhibts the same problems.

Tyler

[8upZR1]

I agree. I believe the crank and cam sensors are good. I used the ISS in check mode and the green lights flashed indicating that the sensor output was good. The lights only flashed faintly, but they did flash, so I assume that they passed whatever testing the ISS machine performs. Tyler please PM me with your address so that I can return the ISS and scope. Thankyou again for letting me borrow them.

ZR1 MK are you still willing to instal my DIS in your car to see if it is good?

As for the lean starting condition, I don't believe it has anything to do with the problem. The injector spray pattern looks good, noid lights check out good, fuel pressure is good. Earlier today I sprayed extra fuel into the manifold from my NOS system, two 0.018 jets, and it did nothing, not even a change in A/F ratio. I guess that means that the fuel is burning up in the manifold. So I am back to thinking that the timing is totally F'd. Somehow the spark is coming as the intake valves are open. Perhaps I will try swapping plugs. Swapping CYl #1 @ 6 deg BTDC with cylinder that has intake valve open. Dunno if it is worth the effort but at this stage I am trying anything that could remotely be possible, no matter how unlikely.

[ZR1 MK]

Originally Posted by 8upZR1

ZR1 MK are you still willing to instal my DIS in your car to see if it is good?

Yes. I remember the DIS located under the plenum and being able to unplug from the wiring harness. Also, will your 1991 DIS (if I remember correctly) work on my 1990 engine? Some say the part number for 1990-95 is the same, while others say they are different. We need to confirm this. Keep in mind, for shipping cost and time frame, Im located in NY. I will be available after Im back from my next track event that puts me home on July 18.

[8upZR1]

ZR1 MK my car is a 90, so no problem there. I will PM you tomorrow about specifics. I have since ordered a new DIS with many prayers that it is in fact the root of all evil concerning my problem. I am at this point doubtful that the DIS is bad though. I am thinking more and more that I have some other issue.

I was wondering if it would be possible to start the LT5 by unplugging the ECU all together and leaving the DIS plugged in. For fuel I will spray the wet side of my NOS system. All I am really hoping to accomplish is to cut off the fuel injectors without removing the plenum and actually unplugging them from the harness. Will the DIS produce a spark without the ECU? I am thinking that maybe the mixture is way off and if I could adjust it with pills to get it in the ballpark I could go from there and find somebody who would be willing to burn a chip with less fuel without actually having to have the car in front of them. I am not looking for the car to run on the nozzles, just sputter a little to let me know that it is in fact the A/F ratio that is holding me back.

Another thought of mine concerned the hydraulic cam followers. Can they pump up? If so can they pump up to the point that the intake valve does not close? I was thinking maybe the intake valves are staying open and that is why I am getting combustion in the ports. Silly thought, but I have not much else to think about these days.

[ZR1 MK]

I wounldnt run the car by disconecting items you mention. Also, if the lifters operated fine before, they will be fine now.
If you want, give me your phone number, or you can call me.

[8upZR1]

No need. I think it is F'd, totally F'd. I cranked it over today and it sounded kinda funny, like something was missing. It almost sounded as if the motor was spinning freely. It was distinctly different than ever before. I checked all the usual stuff and everything looked OK. Then I ran a compression test and behold, one cylinder gave 30 psi, the others only about 5. About 2 weeks ago I checked the compression and it was in the high 180, low 190 range. I did not hear anything bang or clunk, the starter did not even seem to strain. I am guessing that the whole thing is trashed. OH well. I would like to thank everyone who gave their input on my previous dilema. Earlier in the week I was thinking about how difficult it would be to swap out the LT5 for an LS series engine. I have come to the conclusion that it would not be worth the trouble. However, I have located a suitable SB2.2. Its 355 CID, 820HP, carb, distributor. A nice piece. I am thinking that maybe the trouble will be worth the final result. At least I wouldn't be thinking about ignition modules, and computer jive. I have researched this today and it seems that the parts that are incompattible can be swapped with those from an LT1 car without hassle. I hate this LT5.

[tccrab]

This is sad news indeed.
Are you SURE that the compression is lost, and you don't just have leak in your compression tester?

I'd *really_really_really* hate to see you give up after so much time and effort that you've spent, and no doubt a small fortune that you've had to dish out.

Get a second opinion before you give up the ghost.

Surely there's fellow ZR1'er somewhere reasonably close by you that can lean on for support.

Guys?
Are you listening?
Time to step up to the plate!!!
One of our own is ready to lay down his arms in defeat.

Tyler has already stepped up and sent some test equipment, is there anyone within reasonable driving distance who has the experience to help this guy diagnose/repair his baby?

It'd almost be a sin to drop in one of those ugly new generation small blocks, although a new LS7 at 550hp would almost make the ugly bearable....

I'd offer to drop on by, but California is a long_long way from Georgia.

'Get 'er Dunn!

TomC
'90ZR1 #792

[8upZR1]

Its OK. I still have a Mustang that is plenty fast. Maybe some day I will find the motivation to tear the motor apart again. Its definetely toast. I checked the Mustang with the same gauge and its working fine. I guess I just tried cranking it over one too many times. Sounds kinda like a 928 with a snapped timing belt, although I doubt the chain broke, but with my luck anything is possible. Where I live I am the only person with a ZR1 for at least 100 miles. Even the Chevy dealership here thinks ZR1 means 16 valve pushrod motor. To say its kinda backwards, backwoods, backside is a total understatement. Again I thank everyone who tried helping me out. Special thanks to Tyler for sending the ISS, he doesn't even know me and sent out a package, total class act. Tyler for president. If I ever get the ZR1 running I will post.

[tomtom72]

I would just like to say how badly I feel for what has happened to your Z.

Good luck in your future plans!

Tom