IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: Tim Hensley on February 20 2014, 01:16:53 AM
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Car runs good BLM 125-130 all the time.but at idle it will stumble here and there,fuel pressure gauge will drop or jiggle 1to 1 1/2 lb
could it be reg or pump
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Hey Tim, what brand of FP regulator do you have installed? A large group of members running the Accufab unit seem to be having some suspicious problems with these. Kirbans' billet aluminum adj FP regulator looks to be the recommended cure.
Can you tell us what brand of fuel pump is installed? How old & how many miles?
dave
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I don't see any reason at this time to suspect the regulator, and very little to suspect the pump at this point.
What does the voltage to when it stumbles? Don't rely on the scantool voltage. Connect your meter to the fuel pump test connector under the hood and see what happens when the stumble occurs.
Also watch your scan tool readings for maf, o2, and iacs to see if there is a fall out on one or all associated with the stumble.
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Fuel pump test connector ? Fuse block on alt?
Working on laptop I hate Windows . The old Dell field agin
Looking for something different so I can look at those happiness so quick I really don't see any thing on Scanner
It is accufab hot wired all five year old 4000 miles old
Thanks
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the fuel pump test connector is the single gray wire that comes out of the wiring harness at the front of the driver's side valve cover. the Tach test connector is the other one that comes out there but it has two wires going to the connector and they are white...
If you like, connect the meter at the back of the car where the fuel pump connects to the hot wire
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I know that wire
That's what it dose
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apply 12 volts to it and the pump will run...
Or, when the car is running, it will have 12 volts on it from the factory fp relay
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start up volt 14.2
water temp 160-165
volts drop to 13.8 ,steady at stumble
AF 6-7-steady
IAC 40-46 it will jump up 1 or2 at stumble
O2s 12.9-13.1 steady this seems rich at idle
my INT and BLM steady 125-128 at idle
My cruse BLM 125-130
forgot fresh engine 200 miles
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what are the factory O2's?
and what does the fuel pressure read when you pull the vacuum hose off the regulator, and does it still stumble when idling with the hose off?
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and...try setting the iac..sounds like it is way high...should be closer to 10-20 on a warmed up engine...in park and no ac
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forgot fresh engine 200 miles
Has the oil been changed (and inspected) yet?
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740
43
Yes no Change
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Yes on the oil inspection
First at 15 min tinny tiny bits of trash
Second oil change 30 min no trash at all
3ed at 35 miles spotless
Tomorrow 200 miles will see
Got 250 on it as of today
Runs good temps BLM all look good just has a funny stumble her and there
Grab the wires no shock Autolights 25p got NGK
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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?
When you are adjusting the iac, take it all the way down to zero and see if it acts up then
does it do it at higher rpm?
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Been watching this thread...and I think Steve's right. Sounds like Dans car...traced it back to a broken IAC wire just where it went into the weatherpack connector.
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I would tell you great minds think alike, but, I am getting more feeble minded each day, I think
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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
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plugs 5and 6
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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.
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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?
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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 :D
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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
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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.
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Far as I can tell from his comments, it does :)
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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
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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
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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.
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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