|01-07-2012 08:42 PM|
|40 grey||UPDATE: EGR valve finally showed up and was installed today. Made sure passages were clean(it was). Night and day difference. Problem is completely gone and truck is smooth again! Thanks to all who offered help, it never hurts to have more info.|
|01-04-2012 10:34 PM|
|01-04-2012 09:06 PM|
|40 grey||I do not own the GM manuals. I do have an old, well used and trusty Motors manual. But I do have access to the GM manuals through work. Through these and an old Snap-on scanner most things can be observed/tested, even if it is done crudely! I have a fair amount of experience with junk and low budgets.|
|01-04-2012 08:55 PM|
|01-04-2012 08:43 PM|
|40 grey||Will do. Intake was hot tanked with the rest of the engine parts at rebuild, so I'm pretty sure it's clean. But will check at install. Thanks.|
|01-04-2012 08:24 PM|
|EagleMark||and make sure the passege in engine is clean/not plugged!|
|01-04-2012 08:18 PM|
Thanks to all for their help and suggestions. After further testing and retesting, the EGR valve was found to be intermitantly sticking open when solenoid commanded it open(cruise over 40mph). Oddly enough it would manually test okay, held vacuum, and pintle moved freely off the truck. When on the truck it would sometimes not seat or open freely after it was hot. New one(ac-delco) is coming tomorrow. Hopefully this is the problem. ---
---BTW, it ran pretty good with automatic ecm and prom. Low idle(500rpm), and shift light on steady were only observed problems.-----
|01-01-2012 06:09 PM|
VSS on a lot of Chevy trucks is in the speedometer.
700r4 does have a park/Neutral switch and also a brake switch, when brake off TCC will lock up, when brake on TCC off. HTH!
|01-01-2012 05:14 PM|
what are the odds that the knock sensor is acting up?Just a thought.
|01-01-2012 05:08 PM|
Standard tranny has no torque converter.
700r4 does not have the shift position/neutral safety switch. You're thinking of the later 4L60e.
1989 700r4 should have the VSS. Not sure how the signal from the 5 speed is done.
|01-01-2012 10:37 AM|
After re reading this post it occured to me that what youre describing sounds like a torque converter lock up shudder and not an electronic problem.
depressing the brake pedal unlocks the converter to aid in braking the vihicle. Why I mention this you ask?
If you want to determine the torque converter is the problem, drive the vehicle, you will need to use both feet. Run the gas with your right foot, when the problem starts acting up, lightly touch the brake so as to disengage the torque conveter, if the problem quits when you touch the brake then the issue is with the torque converter.
If that is the case,a fluid change would be a possible fix.50/50, either it will or it wont.Its the least expensive thing to try.
If that doesnt fix it, you may need to replace the torque converter.
|01-01-2012 10:29 AM|
|12-26-2011 07:44 PM|
The ECM from the truck with the 700r4 will require a signal input from a shift lever sensor to tell the ecm the truck is in gear. With a standard you wont have that. The timing curves between the 2 computers will be noticeably different due to that alone. The computer/prom from the auto trans model may seem sluggish.
However it could still provide you with a usable test result if the misfire, bucking, jerking goes away. If it does, then swap the PROM over to the replacement ECM and drive it again to see if it is still OK. If it is, That would indicate the trouble was the ECM and not the prom.
|12-26-2011 07:27 PM|
|40 grey||Okay, thanks for the help. The alternate prom (and ecm) is out of the same year truck with a 5.7 and 700r4. Known good(or atleast was), took it out myself from running truck. My truck has a 5-speed, don't know if this will make a big difference as far as diagnostics are concerned. But thanks , I have some more things to look at now.|
|12-26-2011 07:01 PM|
This may help ID your unit
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