1985 Chevy S-10 High Idle

[Tim Martin]

I got a customer that has a 1985 S-10 Pk Tk with a 2.5L engine and a 4 speed manual transmission. The issue it has had for several years now is that when the engine is started up, the high idle speed is 2,200 rpm. The high idle eventually goes back to a more normal speed as the engine warms up. Now I know that upon startup, most fuel injected engines will have a high idle comparable to the choke being on a carburated engine. This truck has been to many shops in the area to find the problem with new parts installed such as plugs, wires, idle air control valves, throttle bodies, ecm, fuel pump, filters, distributor cap, rotor, coil, ingition module, coil pickup, cts, iat, o2, sensors being replaced. Even if the engine is started and it is, say 125 degrees it will race like that for a minute or so. You can go down the road in first gear at 35 mph. What am I missing?

[timjlive]

I had one similar to this several years back. It was the IAC. Any aftermarket IAC valves we tried would not bring the idle down correctly. After beating our heads we put in an OE and it worked like a charm.

You say "The high idle eventually goes back to a more normal speed as the engine warms up." More normal mean close to spec or within spec?

What about the PCV valve? I've seen them loose their insides and create a hell of a vacuum leak.

HTH

[Tim Martin]

Normal idle speed as within specs as engine warms up - 2-3 minutes. Pcv valve has also been replaced. I do not know what brand of iac the other shops were using but i may see if it is an aftermarket brand.

[steven kiser]

the normal idle may in fact being controled by the iac. if you have an intake leak ( very common) the iac will compensate for it. it's doing it's job, controling the idle for optimum performance. a quick check would be to see if the positioning poetion of the heating system is working properly. is it's defaulted to defrost tou have a vac leak. the air going through the throttle body along with the iac opening to prevent stall will mask any vac leak. check the 11/32nd vac hose on the rear portion of the intake. good luck.

[brianp87]

yes check for an intake or vacuum leak

[Tim Martin]

Yer saying that 1 vacuum leak on a 11/32" line will cause it to rev to 2,200 rpm? Just kidding! But what you are proposing may be the problem. I will check it out now that the vehicle is in my shop till it is fixed. Thanks for the input.

[brianp87]

I would spray some carb clean around and see what you find

[steven kiser]

normally i would agree with the carb cleaner but on an older car like this i'de be carefull of leaking ignition wires. i've seen throttle body gaskets (rarely) leaking. mostly i find the bottom of the intake gasket on # 4 missing or the vac feed off the rear portion of the intake (after throttle body) rotted, collapsed and leaking. also check the elbow at the pcv. good luck.

[brianp87]

You can use propane also this old thing I would be careful but I would bet it is a vac leak all the other places wanted to do was swap parts. You could have a defective new part but I would lean towards a vac leak

[Tim Martin]

Yea, it's interesting. Many shops in our area here simply want to replace this and replace that. Then when the customer has spent yea how much money and is irate, then he comes to me and wants me to be considerate of the fact that he has already spent soooooo many dollars and the thing still is not fixed. Talk about a guy getting ripe; thats when I lite up. I got to get this thing and try the propane act, maybe Monday will have more time than today.

[steven kiser]

tim, you hit a huge * of mine square on the head. on occasion i'll have a truck or car roll in where i'm the next in line of a list of shops that have already thrown parts at it. the customer has already dumped hundreds and hundreds of dollars at it with no help. they look at it like it's been at my shop all along and don't wnt to spend another dime and feel they've been screwed. before i even work on it i'll explain that once we've pinpointed the fault i will not attempt to repair it unless the customer is willing to allow me to make sure that all previous repairs pass my quality guidelines. if they refuse i'll tell them i'm done and please come and get it. no matter how much they assure me that they understand that something that was previously done improperly can cause a future issue and will not try to hold me responsible i won't work on it. i've learned. in the past i've repaired vehicles in this situation where an inferior part fails in the near future and the person is all over me because i was the last person to work on it and because of that it's my fault. i've had trucs come in where thousands of dollars have already been spent on it to repair a problem with no positive results. when the person called and booked the appointment i've already diagnosed the problem in my mind as a blown fuse in a fuse box that's buried in a cluster in the drivers side frame rail. the truck comes in and i see a new alternator, battery, glow plug relay, connector at glow plug rail and the wiring harness opened up like a fish at the warf. am i going to replace the fuse and send it on it's way? unlikely, unless the parts are of exceptional quality and i'm allowed to inspect and repair harness, if replaced parts are from wally's reman euporium i won't touch it unless i'm allowed to replace the crapolla parts with quality reman or oem. i know that when i tell the customer it was just a blown fuse i'm going to be the target of a huge amount of frustration and possibily the person they come to when wally's reman either fails or flames up like an over saturated bbq pit. the quest for quality in parts and technical ability is sometimes as frustrating as it's costly. there have been times that i'll install a quality part and spread the increased cost throughout the order just to appease the customers dollar restrictions. i will not allow monetary restrictions to effect the quality of my craftsman ship. whoever said being a shop owner was easy was dead wrong. gotta cut it off now, i feel a long babble and emotional dumping coming on.........................................................

[Tim Martin]

What really gets me is that at times the customer will not believe that it could be something as simple as a blown fuse or the likes. There is when i got to walk away for a few minutes before I respond to the customer. My grandpa used to say that when angry count to 10 before speaking and when very angry count to 100. I don't literally follow that advice to the t but I use the principle of keeping my cool to a customer. More often than not, it is harder to relate to the customer than to repair his vehicle. I got this notion that us independent shop owners are some of the most talented men on God's green earth. Not only do we have to keep current with the complex technology on today's vehicles but we got to be a public relations person, we got to be a lawyer, we got to be an accountant, and the list goes on. My gripe is that we never get paid for what all we have to do. I think I am going to learn to be an undertaker. --------- No complaints from dead people!!!!!!!

[steven kiser]

i have a friend that runs two cemetaries. he always says "i'm the last person to let you down" he tells me of sme of the complaints he gets. he had one family that wanted the grave moved because the surviving spouse discovered that the grave beside their loved one contained a family member of a long hated family. he say's it's not the tennants it's the tennants family.

[Tim Martin]

I guess no matter what business one is in there is someone that will not be satisfied. hmmmmmmm. Well, well. And, like it or not, most of auto repair shops get lumped into the same category of rip offs, money launderers, and the list goes on, even though the vehicle is fixed. But hey, mom said there would be days like this. She didn't tell me that they might come in bunches like bananas.