Hello everyone and thank you for your time. I recently purchased a 1990 Chevrolet k5 blazer 5.7 TBI 4x4, its the 1st truck I've ever owned, it has been my dream truck all my life,ever since I was a kid seeing them with a backseat and the top off. Ok, so Issue 1, so while sitting in Drive the idle surges and after about 15 seconds it will die, and will start up and run just fine until its in drive sitting at a light. But in neutral it will stay running with little to no surging. While driving it has no hesitation or stumble while driving hard or light. I have hooked up my good old snap on brick scanner put it in field test mode and everything seems to be functioning fine, with no codes stored in history,idle is at 900 rpm in park. Spark plugs look fine, with no signs of running too lean or rich. The Fuel injectors are spraying fuel evenly at idle and under load. I am very mechanically inclined but I want more opinions then just my own. Or maybe somebody who has had this exact same issue could shed some light on this topic. But judging on my diagnosis,which could be wrong maybe the IAC is acting up. I'm not a 100% sure. So if anyone has any information for me I would greatly appreciate it. Issue 2 does anyone know a website where I can order the side glass for the removable cap for the RR. I haven't had much luck finding any sites that sell it. So if anyone has any information for me don't hesitate, it would mean a lot to me if I got some responses. Thank you everyone




Greg

 

map sensor sticking possibly? if you have access to a data stream type scanner it would be nice to be able to check everything.

another issue these engines had was the temp sensor for the computer would go bad and tell the engine its like 10 degrees out when its 80.

the sad thing is i actually have the exact same engine and really dont know that much about it as i never have any problems with it

 

Yes the temperature sensor could be a possible, most people forget about how important that sensor is, but I'm leading away from it because it's not running rich and drowning itself with fuel. Like it would do if it was -10 outside. But on my day off I'm going drive it with the scanner hooked up and catch it idle surging while hooked up to the scan tool. I only checked it out while in park at idle. There is so many reasons why the idle could act up ,vacuum leaks, Egr,Iac, tbi gasket leak, etc. etc. And yes that scanner is a lifesaver. I only have obd1 cars so that's why I bought it. The same scanner is on ebay for cheap under 200 bucks worth every penny if you were interested in one. Its called the snap on brick scanner looks like a red brick just in case you didnt know. I really appreciate the input on this. I was hoping this is a common thing with all k5's and all of them have the same fix, that's more or less what I was asking. But thank you so much for your input




Greg

 

Well thanks anyways guys, problem is fixed it was a bad Idle air control valve.

 

i was gonna say iac. did you try cleaning it? 90% of the time they get dirty. $3 brake cleaner fixes it.

 

Nope went and bought a new one, but I kept the old one. Its so funny you mention clean it because I was going to do that, but figured it wouldn't of worked anyways. When I had it hooked up to my snap on brick scanner while in drive, the iac would function normally then go to iac position 4, 2, 0 then die out, while sitting. Figured it has failed. I also replaced mostly all the vacuum lines, most of them were in terrible shape. Now I have to find a company that stocks that side window glass. I've contacted glass company's, nobody can order it. Looks like I will have to keep my eyes open at all the local junkyards.

 

Lmctruck probably has it

 

That's the first place I looked and they have the side window listed for the 76-91 suburban but not the 76-91 k5, you can look for yourself. Its my luck so im not really shocked.


Truck Parts and Truck Accessories