Success at last!!!! (I hope...)

[tccrab]

This is a long story, so I'll try to keep it interesting enough to read.
(Cliff Notes are at the end for those who are reading impaired.)

I've been fighting a gremlin for going on 3 years, the two major faults were an intermittent rough idle and a really annoying heat related misfire.
The misfire would present itself after 30 minutes to an hour of driving.
It would start out as an occasionally little hiccup that would grow into full blown epileptic fit.
I'd shut the engine off and after cooling off for an hour or so she'd run fine again.

I've spent endless hours and more money that I'd like to admit trying to figure it out.
3 plenum pulls later, new coil packs, spark plug wires, spark plugs, tried two other ECMs, endless hours of tinkering and gobs of frustration and still no joy.
I was *This Close* to sending the car up to JeffVette for him to figure it out, having reached the end of my rope.

Then back in October, this posting from Spanky1965 caused me to pause and start thinking.
http://www.zr1netregistry.com/forum/...8&postcount=39
He too had been plagued by an ignition gremlin that refused to be fixed by throwing new parts at it.
At the end of the day it was an ECM pin with a bad connection.
...hmmmm.....

Now bear with me for a little longer, here's where it gets interesting.

Three years ago, I had injector woes and wound up replacing the original Multecs with Accels. After replacing them I still had a misfire so I wound up buying a remaned ECM from the local Chevy dealership. The misfire went away, but sometimes the idle would surge and I'd hear a little Dual Mass rattle. The heat related misfire manifested itself around two summers ago, and had been getting worse and worse ever since.

I called up good 'ol JeffVette and talked to him about the possibility that I'd fubared the female pins of my ECM plug when I tested the old Multecs.
Back when I was trying to figure out which injectors were bad, I had just shoved the probe of my DVM into the ECM plug to measure the resistance of the coils in the injectors.
Never once noticing that the diameter of my DVM probe was twice the size of the ECM male pin....

Before Christmas, Jeffie sent me his fancy crimping tools and some replacement pins, but the holidays got in the way and so it wasn't until New Years weekend that I got around to checking out the pins.
Sadly, the replacement pins Jeffie sent me weren't the right ones, but I was able to find the right ones at EFI Connections:
http://www.eficonnection.com/eficonn...terminals.aspx
The pins for the '90s and '91s aren't on their web page but they do have them in stock at $.45 each.
I started checking the ECM plug pins and lo and behold, 6 out of the 8 primary fuel injectors pins were so sloppy that they wouldn't even hold onto the ECM pins. You could put them on the pin, turn the ECM upside down and they'd just fall off.
Anyway, I checked all the pins in the plug and found 4 more pins that were sloppy loose.

Car runs fine. No more idle surges, no more occasional dual mass rattle, and NO HEAT SOAK MISFIRE.... (so far...).


Cliff Notes:
Shoved too big a probe into the ECM plug and stretched the female pins in the plug to the point that they weren't making good contact with the ECM pins causing intermittent rough idle and heat soak misfire.
Spent time and $$$ throwing new parts at the problem without any joy.
Replaced stretched pins and problem seems to be gone.

Lesson learned:
Don't shove things that are too big into holes that are too small or it will cause you lots of problems and cost you big $$$.


JeffVette: Many, many, many thanks for all your help and for your patience.
Your tools are on their way back to you.

TomC
'Crabs

[flyin ryan]

Lot's of pain, but happy ending...Cool . Thanks for sharing with everyone.

[tomtom72]

Oh man, that did drive you crazy for a long time! Glad you did find the cause & corrected it!


I don't know how many times I've read the phrase "back probing the connector will allow...." and I'd look at the connector in question and look at my test light and think..."no, this is not a good idea Tom!"

Phone wire & a small needle nose or tweezers works nicely with out distorting the original connections.


Tom

[secondchance]

Originally Posted by tccrab

Lesson learned:
Don't shove things that are too big into holes that are too small or it will cause you lots of problems and cost you big $$$.

I will try to remeber!

[GOLDCYLON]

Originally Posted by secondchance

I will try to remeber!

-
Yeah TC cracked me up there as well. Great follow through TC. I hate electrical gremlins

[bdw18_123]

Cool, you found the problem! I bet your really happy now!

But your problem is what made me discover a problem with my Z that I didn't even know I had. If I hadn't sent you my ECM to help with your troubleshooting, I wouldn't have known that my ECM would make the engine run with a bad mis-fire.

I would have been tearing my hair out trying to fix my mis-fire problem once I got the Z back together. I bought Sgreg's ZR-1 ECM, so I've got that problem taken car of.

Thanks Tom, for taking my ECM up to Jeff to confirm my problem, the brotherhood is awesome!



.

Originally Posted by tccrab

JeffVette: Many, many, many thanks for all your help and for your patience.
Your tools are on their way back to you.

TomC
'Crabs

No problem Tom, now go out and flog the bitch!

[rhipsher]

[QUOTE=tccrab;78911]Don't shove things that are too big into holes that are too small or it will cause you lots of problems and cost you big $$$.
Well that depends. Usually it feels better. And if it doesn't fit at first just tell her to relax a little. Everything will be just fine.

[bdw18_123]

Originally Posted by rhipsher

Well that depends. Usually it feels better. And if it doesn't fit at first just tell her to relax a little. Everything will be just fine.

[tccrab]

Well that depends. Usually it feels better. And if it doesn't fit at first just tell her to relax a little. Everything will be just fine.

TomC
'Crabs