Fuel Pressure Regulator,stumble

[Steve Wood]

I would tell you great minds think alike, but, I am getting more feeble minded each day, I think

[Tim Hensley]

wiggle test no change
puled plugs # 5 just a little lean
lifter pre-load .025
Ill put some more miles on it next week
cant figure how to post pic of plugs ill figure it out

[Tim Hensley]

plugs 5and 6

[Scoobum]

I would tell you great minds think alike, but, I am getting more feeble minded each day, I think

Don't sell yourself short. You're still as sharp as a tack.

[Scoobum]

Not very scientific...b ut a times like this I start swapping crap out one item at a time. I have multiple spares of everything...s o I can swap the stuff out pretty quick. I had a miss in my car a while back. I made a PL file and Norbs and I had a look at it. TPS looked like a sawtooth pattern instead of smooth. Swapped out the ECM and made another PL file. TPS looked normal. Norbs figured something went bad in the ECM. Gave it to him...but I don't know if he ever got to checking it. You don't have PL do you?

[Steve Wood]

I don't believe it is the regulator or the pump....sounds like something electrical.  If you wiggle each injector harness connector, does it cut out while wiggling?    No Change

When you are adjusting the iac, take it all the way down to zero and see if it acts up then   Not tested?

does it do it at higher rpm?  Not answered

I always do my best to use logic to narrow in on the problem just like I would if it were my own car.

Initially you said it ran ok but had a stumble at idle.  You wanted to know if it could be a regulator or fuel pump problem.  I asked a few questions to try to see if there was any indication of that and the results seemed to indicate to me, at least, that those two items were probably not the cause.

The key to me was if it did not do it except at idle, then it was probably something that only occurred at idle and the iac is one of those things.  I asked for confirmation that it was idle only because I have had people say something only happened at certain times when they meant that was when it was most obvious.

I asked you previously to reset the IAC because the readings were way high for what they should be on a warmed up engine and I asked this time for you to screw the adjustment in far enuf to get to zero on the reading to take it out of the equation knowing that if the throttleblade controlled the idle instead of the IAC, and the problem  went away, then the fault would be narrowed down to the iac or the associated wiring.  I think this was what Brad was wondering as well.

Maybe it is time to start swapping parts, sometimes that is better than me getting frustrated trying to simplify troubleshootin g

[Tim Hensley]

At cruse i fill no stumble 1500 rmp
penny in the stop 3000 might here it but ill say no
Ill adjust the IAC closer to 0 today
I have some spears
after pulling the vacume line off the reg and it stumbled but pressure did not move i felt it was not the pump or reg
I hope to get a computer running this week to log
I pulled the plugs to look at the  combustion chamber
thanks for the help I will get to every thing on the list

[earlbrown]

after pulling the vacume line off the reg and it stumbled but pressure did not move i felt it was not the pump or reg

You need to focus there until you get the fuel pressure to accurately track vacuum and boost.

[Steve Wood]

Far as I can tell from his comments, it does

[Tim Hensley]

have not had time to set IAC 
work mat working on lap tops to log, drove the car to work to try them ,car runs to good at  cruise
will get to adjusting it  tomorrow
I wiggle test every time the hood is up

[Tim Hensley]

Got time tonight to set the IAC
set at 10-12 after wormed up
reset TPS to .42 WOT 4.4
reset computer and double  checked all good
took it out for a drive came back let it idle for 10 min. it s good and stumble
IAC and TPS holding good
Thanks for the help Ill keep you posted
It seem to have done it I cant understand how

[Steve Wood]

If the problem was/is only at idle, then the only thing that affects idle is IAC.  The ECM is trying to maintain a steady idle by changing the duty cycle of the iac...the lower that you set it, the less control the ecm has..when you get to 00, the throttleblade is right on the verge of controlling the idle rather than the ecm.

I was expecting it to run okay at 00 indicating that the wiring was bad or the iac, itself, was bad.  I would expect it to be less obvious at 10 but not be completely gone.

[Tim Hensley]

was looking at some old logs IAC was low 20s
then I realized I removed the PCV this is why I needed more throttle blade and IAC so high
Im sure the IAC is working ok I put it in gear RPMs drop then IAC count come up and idle 780 turn on AC same
I forget IAC # 19-25 I think is what i remember but was moving  up and down under different conditions