stalling problem

Falco

Falco

Donating Member
Howdy,

I'm figthing against a stalling problem for a while now. It has became worse and worse, so I'd appreciate any idea to solve this...

Let's see. Beside this stalling problem the truck performs very well. WOT performance is better than ever. It's running like a champ. Stalling happens when the truck is up to operating temps, not when cold. It usually happens when I'm changing gears, but sometimes after a hard braking too. When the truck warmed up the idle is also erratic, hunting between 725 and 850 RPM. AFR (according to the wideband) is also hunting with it between 14.9 and 16.5. Vacuum is also fluctuating a little between 19 and 20 psi. Water temps always below 165F.

I've made a bike tube test and a real close visual check, couldn't find any vacuum leak so far. I've also tried to spray WD-40 around the gasket at both the lower and upper manifolds while the truck is idling. No change in the RPM so far doing this. IAC also seems to be doing his duty, it's between 35-39 at idle. So I'm pretty sure that's not a vacuum leak.

Ignition is new from the distributor to the spark plugs and as I said WOT performance is awsome. I guess an ignition related problem would show up at WOT first.

I started to use xylol, before I started to experience this problem, but now it shouldn't be any in the tank. Also changing to the Ultimate 50v4 (was running v3 before) and tigthening my plugs' gap to 0.032 made this problem worse (or maybe that's just a coincidence).

You can download a zip-ed run from here:

http://www.tragacs.com/Download/photo.zip

It dies at the end while I'm changing from P to D. It also has a short WOT blast. I'd really appreciate any ideas... This has a big impact on the driveability of the truck...

TIA,
 
Falco

Falco

Donating Member
Bill,

Thanks for your input. Actually I just lowered my fuel pressure, becuase I thought it's too rich. The base pressure (vacuum line disconnected) was 52 psi, now it's 48 psi (keep in mind these are not stock injectors). The funny thing it seems to be helped a bit. The problem is still there, but not that bad than with 52 psi. I don't know... According to you I could try to make it richer, go above 52 psi, but this seems to be on the high side. Or I could go lower than 48 psi. What are you guys running with the 50's and high pressure walbro?

Later,
 
ed hess

ed hess

race or get outta the way
falco

I think i just saw a post were you were looking to change your tb cuz of shaft leaks.

well fwiw, i know you recall my very long stalling thread last fall.

when the new motor was done all the ignition stuff got reused, cap, dist, wires. All sensors got reused inlcuding o2. same ecm. different plugs cuz i had vortecs on the new motor. All vac lines were reused cuz they were new also.

You would think that my stall problem wouldve transfered to the new motor.

It didnt!

The tb was changed on the new motor, so no shaft leak.
other than that I have no idea why it stalled before.

you probly recall turbo tony had me go thru each and every item in the truck. Everything got replaced.

only other thing beside the tb i can tell you is:

when i went to remove the lower intake to sell it, After taking the bolts out (they had been retorqed looking for the stall problem) i was able to lift the intake off the motor with one finger! the seals were not even bonded to the heads any longer!

vac leaks never showed on a gauge, or bike tube test.

I wouldve taken the motor down to this level in an attempt to resolve my own stall problem but never took the time since a new motor had been planned.

Not suggesting this is your problem, just somthing to consider after you fix the shaft leaks on the tb.

hth

ed
 
Falco

Falco

Donating Member
Thanks Ed,

Yep, this is the number one reason why I want to replace my TB... However before I spend the money I'd like go through on all the free suspected solutions...

Later,
 
D

denny

Active member
Re: stalling problem

I start having and still have this stalling problem after swiching over to 50lber.
Changed all "ignition stuff " and even try a different chip.

Let us know what you find.
 
HighPerformanceTrucks

HighPerformanceTrucks

Lift & Shift Specialist
Re: stalling problem

Hey guess what? I tightened the bolts to the throttle body and the top plate on the throttle body and my stalling issue went away.

Thank god for forum search!
 
gjp

gjp

another post whore
Re: stalling problem

I have the same thing going on. I will add that to my to do list this weekend.
 
nightdiver

nightdiver

Active member
Re: stalling problem

hunting with it between 14.9 and 16.5. Vacuum is also fluctuating a little between 19 and 20 psi
Click to expand...

come on guys ............the truck is beging for some fuel here. With this vaccuum in a camed truck there is no way to have a leak.
Get the truck running at idle with14.2-14.4 :1, then turn on all the accesories and lights , put the truck in D and watch what will the afr be. If you still have problem then mod the throttle follower map. This map pulls the iac back so when you hit the pedal the iac will allow more air to pass. This way when you let off the gas the iac needs some time to reach the preset point and this is why you wont have any stall right here
 
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