J
JURB6006
Guest
Hi :
The van pulled up semi-lame recently. The regular mechanic wanted to put an
engine in it and being a 99 GMC 5.7 Vortec you know what that costs.
I decided to loan the shop my personal mechanic, but I'm handling some of the
troubleshooting. It had a dead miss, one cylinder only reading 50 lbs
compression and a pretty bad sounding knock on heavy acceleration. (this is
almost all the time because it's a cube van, dual wheel with a gnarly lift
gate) This knock was clearly in one cylinder only. I say was because it doesn't
run now.
In the interim I actually did hear it run and I wanted my mechanic to hear it
run before tearing it down, but over a weekend it stopped running. Absolutely
nothing was done to it during this time, and I suspected sabotage, but a close
inspection revealed nothing.
Later we found out about the disintegrating computers, placed so well under the
master cylinder. It was obviously bad. This was after they changed the ignition
module, but that was after it quit running. Now with the new computer and
ignition it still doesn't quite start, OK I told him to put the old ignition
back in. He did and then he says "it's like it's worse, it tried to start
before".
Next thing is to put the new ignition module back in.
Now, I wasn't there, but he told me the computer had this instruction sheet on
how to recalibrate for the crank sensor timing. OK, I look on the web and I
found a little bit on it, but everything I've read indicates it is done with
the engine running. If so, dead end.
I queried, what do you mean it does less, they both don't run right ?, right
but with the new ignition you could hear something going on. It popped into my
head to ask "like when you rebuild an engine and you have to re-drop the
distributor (180 degrees out)?" . His answer wasn't kinda maybe, it was yes.
This computer incidentally needed to be programmed before they could give it to
us, and they needed the VIN to do it. I also found that there is expensive
software involved with expensive updates. I wonder if there was a slight error
in the programming process. There could be one bit not set right, just like a
distributor to the engine, even if you know # 1 is at top dead center, you
don't know where the cam is, so those of us who did alot of car jobs in the
past recognize the symptom.
I wonder if it's worth it to redrop it 180 out. I'm quite reluctant to do that
without more information, but on the bright side I can always return it to the
original position. Also, this thing might be taking me for a walk down the
"garden path" here and I really don't want to get lost.
There is one other possibility I'll have looked into, possibly the IAC got
jammed in by the defective computer, if so it should start at ˝ throttle.
Simple test, just gotta do it. I'll keep you posted, but if anyone has any
better direction for me, I'll go there. There are many specifics I don't know,
especially on vehicles newer than 1995.
Anything you got on this is much appreciated, thanks in advance.
JURB
The van pulled up semi-lame recently. The regular mechanic wanted to put an
engine in it and being a 99 GMC 5.7 Vortec you know what that costs.
I decided to loan the shop my personal mechanic, but I'm handling some of the
troubleshooting. It had a dead miss, one cylinder only reading 50 lbs
compression and a pretty bad sounding knock on heavy acceleration. (this is
almost all the time because it's a cube van, dual wheel with a gnarly lift
gate) This knock was clearly in one cylinder only. I say was because it doesn't
run now.
In the interim I actually did hear it run and I wanted my mechanic to hear it
run before tearing it down, but over a weekend it stopped running. Absolutely
nothing was done to it during this time, and I suspected sabotage, but a close
inspection revealed nothing.
Later we found out about the disintegrating computers, placed so well under the
master cylinder. It was obviously bad. This was after they changed the ignition
module, but that was after it quit running. Now with the new computer and
ignition it still doesn't quite start, OK I told him to put the old ignition
back in. He did and then he says "it's like it's worse, it tried to start
before".
Next thing is to put the new ignition module back in.
Now, I wasn't there, but he told me the computer had this instruction sheet on
how to recalibrate for the crank sensor timing. OK, I look on the web and I
found a little bit on it, but everything I've read indicates it is done with
the engine running. If so, dead end.
I queried, what do you mean it does less, they both don't run right ?, right
but with the new ignition you could hear something going on. It popped into my
head to ask "like when you rebuild an engine and you have to re-drop the
distributor (180 degrees out)?" . His answer wasn't kinda maybe, it was yes.
This computer incidentally needed to be programmed before they could give it to
us, and they needed the VIN to do it. I also found that there is expensive
software involved with expensive updates. I wonder if there was a slight error
in the programming process. There could be one bit not set right, just like a
distributor to the engine, even if you know # 1 is at top dead center, you
don't know where the cam is, so those of us who did alot of car jobs in the
past recognize the symptom.
I wonder if it's worth it to redrop it 180 out. I'm quite reluctant to do that
without more information, but on the bright side I can always return it to the
original position. Also, this thing might be taking me for a walk down the
"garden path" here and I really don't want to get lost.
There is one other possibility I'll have looked into, possibly the IAC got
jammed in by the defective computer, if so it should start at ˝ throttle.
Simple test, just gotta do it. I'll keep you posted, but if anyone has any
better direction for me, I'll go there. There are many specifics I don't know,
especially on vehicles newer than 1995.
Anything you got on this is much appreciated, thanks in advance.
JURB