I've heard that running 91 in a vehicle designed for 87 can cause carbon build up. don't know for sure but i always run 87 since that's what the manual calls for.

if your idle is around 500 on start up then you should do the test procedures for the iac listed in the haynes manual and clean the pintle and the hole in the throttle body that it goes into before you put it back on. because that is probably what is causing your symptoms.

 

Pull the TB and check for carbon build up around the IAC airway. If it's dirty-clean it. Replace the IAC and the gasket. Should solve that issue of cold start in the am. At least check it. That way, your not grasping at straws here. The only way to troubleshoot is to check things out one at a time.

It may also be VAC related although, if you've got a blown plenum or, had a blown plenum, then, my bet is on excessive carbon buildup. Start there.

 

thanks! great suggestions

 

It is the IAC. I am willing to go twenty on top of the previous ten that was thrown in on the bet.

 

ok, I'll check it out this weekend. any thoughts on how hard it is to remove the throttle body? I assume there's a gasket between the TB and the intake; suggestions where I can obtain a replacement gasket? And, if the IAC is bad, where might I find a new one?

 

Did you try replacing the IAC? Did it fix your problem? I have the same problem and after reading your post I replaced my IAC but it didn't help. Maybe I will try replacing the fuel pump

 

check your fuel pressure before you replace the pump. i believe the pump is a couple hundred bucks and if it were me i would want to be positive that its bad before going through the hassle of changing it.

 

I was experiencing long crank times and an intermittent miss. I solved the problem by replacing the coil. Good luck!

 

I have a similair problem related to idling. First thing in the am i have to let the truck idle for about a min then the idle kicks up and settles back at 800. If i drive before that happens it seems to bog out. Could this be the IAC? I'm new to TBI so i am not sure what or where the IAC is. Could some one please help before i blow my trucks brains out???

By the way it is a 95 1500 with a 5.2 All stock parts. Unless Holley didn't come with these OEM....

 

All you need to do to remove the TB is the following:

- remove the battery connections
- remove the air hat / intake
- remove all the electrical connectors that connect on the TB (map, IAC, TPS)
- remove the vac line going to the TB
- remove the throttle linkage cables or, you can simply remove the 3 bolts holding the linkage plate to the TB.
- remove the 4 fasteners that secure the TB to intake.
- lift and remove the TB off the intake
- cover with shop rag to prevent things from falling into the intake.

Installation is the the opposite as above. Torque is 18 ft lbs on the 4 TB fasteners. Note: you may want to verify the torque requirement for the 95 just to be on the safe side. Some were only spec'd out to 8-10 ft lbs. 18 ft lbs is nearly twice that amount. Check the Haynes manual under Gas and Emissions section. It is listed on the very first page of that section. Do check the proper connector orientation for your year too.

-remove all the sensors and set aside. NOTE THE SIDE that faces up on THE TPS SENSOR BEFORE TAKING IT OFF. It usually is the one with the stamped number on the face.
-clean the TB using TB cleaner, Acetone, Mineral Spirits, Brake Cleaner etc. DO NOT USE ACIDS to clean Al TBs. Solvents only for all Al TBs.
-use a brush to rid of all carbon deposits around IAC ports.
-clean the TB plates, bores etc.
-clean 100% until shiny- no dark residual carbon should be left.
Done cleaning. Now, time to get a new IAC and put it on.

1. Lightly grease the o-ring with white grease. Just light enough to create a shine. It should not be loaded with tons of grease. Just shiny looking.

2. Install it. On yours, I am not sure of which way the connector is supposed to face. There's an orientation for those things and, the connectors are supposed to face a certain direction. On a 96 for example, this connector is supposed to face the passenger side. That is the OEM spec. Check Haynes manual.

3. Just tighten by hand using a torx screwdriver. Do not over tighten as you will strip out the casting and it will never work. Just snug will do. When the fastener does not turn any more- stop.

4. Reattach your MAP sensor- this is the largest sensor- to the front.

5. Reattach your TPS to the shaft by engaging the two contact points on the flat of the shaft first and then finally rotating it into position so that the mounting holes are lined up. NOTE THAT THE CORRECT SIDE FACES UP.

6. Get a new gasket at Napa, Auto Zone, Car Quest, etc. Most have them or can find one.

7. Get some Gasgacinch sealer while your at it. Place some GC around the bottom of the TB and on one side of the gasket. Note which side you put it on.

8. Let dry for ten min.

9. Once dry, take the gasket and place it onto the bottom of the TB. SImply align it to the TB bores and AIC airway.

10. Using an exacto, trim as needed so that all edges are FLUSH with the bore and IAC opening.

11. Clean out any debris from the gasket trimming process using a can of compressed air.

12. You are now ready to install the TB back on the engine. Installation is the reverse of what was explained above.

It sounds like a lot because you haven't done it. It is very simple. Any questions feel free to ask.

Chris