Mikezord

Hi Guys and Gals,

I've been on the site many times for a lot of various reasons, but the issue I'm having on my 91 pickup is causing me a bit of headache when trying to research the problem.

My rig: 91 Toyota Pickup, 4 cylinder, 5 speed, 4WD.

My issue: First of all, engine runs great; zero issues during cold startup and runs great while driving. My problem is that after the engine gets to normal operating temperatures, the engine surges while idling. It used to be quite a slow surge, but now its quite a fast surge, going up and down within a second, every second until I pull away.

This occurs if I go to the store and come out and start it up, or if I stop at a traffic light. It doesn't always do this though, it levels out close to 1000 rpm after about 20-30 seconds. It seems to me like something is loose or on the verge of failure.

The weirdest part is that it will surge up and down from about 900-1300 with the brakes on, and about 1500-1900 rpm without the brakes on.

I should also note I'm getting a code 25, 26, and a 52. (Engine running running lean AND rich, and theres a problem with the knock sensor.) I attributed these problems to the fact that the guy that installed my muffler accidentally cut the wire on my exhaust O2 sensor.. or so he says.

After much reading, I haven't got a clear solution to my problem, but I did get a big list of things to check. All the posts I read on this site have to do with rough idle ALL the time, not a vroom, vroom, vroom, vroom, vroom idle at a stop light that eventually evens out and behaves correctly.

Something I've seen on other forums but not this one is a problem with the intake air controller valve (IACV). These are rather expensive to buy brand new, so I'm hoping that removing it and cleaning it and testing for continuity will fix this issue.

Has anyone else had this problem? I haven't been too concerned about it for the past while since it evens itself out after a bit, and I've been getting about 12 MPG on 31" tires; but its starting to get very annoying at traffic lights and warm startup.

Any input would be greatly appreciated.

FourGee6Tee3

I have a similar problem with my 94 22re. When you apply the brake and the idle is lower, put it in 4wd and see if it idles higher (as if you do not have your brake on). This isnt much help, but mabye we can figure out our problem together with more information. I am going to adjust my tps this weekend, other then that I am clueless.
ps. I had recently did the head gasket and all new gaskets on the intake side, It had this same problem before I did the head gasket. I will continue to post with more information. I advice you do the same.
- Zach

Mikezord

Well after writing the post I went home and shot half a can of carb cleaner into the throttle body, it seemed to fix my problem for the rest of the day but it was probably just coincidence; as its acting up again.

Someone mentioned it might be a TPS problem, where the potentiometer may be buggy, so let me know how it goes after you mess with it.

I'm having trouble with my heat as well, I think my water pump is on the fritz. I'm getting leakage through the weep hole so I'm going to inspect/replace that asap. Not sure if it will affect the idle issue or not, I'll keep you posted.

Mikezord

Oh yeah, putting it in 4WD has no affect on the problem.

4Crawler

iTrader: (3)

Idle speed is set too high:
- http://www.4crawler.com/4x4/TLCA_Tru...ech.04.09.html

And check the TPS:
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

FourGee6Tee3

Thank you 4crawler. I will try that as soon as possible. Its a festivus miracle.

heepfan

There are a few things to check. First check the TPS for proper function and adjustment. That will cause your exact issue. Also the mas air flow sensor can cause that too if it is going bad. Those are the two most common issues that cause your issue.

Levij83

I've had that problem for a couple of years on my 94 pickup. Just a few weeks ago my head gasket went out and the mechanic told me that might have caused the idleing problem via vacuum leaks. Along with the gasket there was a bolt broken in the head. That may have caused some of it as the head was seeping alittle. When i had to pull it into the garage the thing was idleing at 3k! As soon as i pushed the brakes it would start the up and down stuff. For a while i thought it might be the brake booster and I fooled around with that and thought i fixed it, but i guess that wasnt the problem. Hope you get it fixed!

Mikezord

Thanks for the replies, those solutions seem like they are worth a shot; however, it might be a little while before I will know for sure. My lower control arm decided to break as I was backing out of my driveway (luckily not in the woods, or on the highway). Anyone know a good autoparts warehouse that ships to Canada?

asaj

Hey, I have had the exact problem on my 87 4runner 22re. Mine problem was that the idle speed was to high. Get it up to normal operating temp and check idle. It should be around 900 to 1000. The adjustment screw is notorius for backing out on itself.

abecedarian

idle on a 22re should be ~750

Bako88

I have idle problems too. That's why I'm looking here. What I do know is that if your engine is idling high and you press the brakes, the fuel cut switch tells the computer to cut fuel @ injectors and your RPM's drop. Once RPM is below 1000 to 1200, fuel is back on and engine idles back up, fuel cuts .....

My 88, 22RE idles up and down slowly from 600 to 1200 and runs rough. Also smells bad while running. I know I need to replace at least 2 large vacuum lines. I have done a valve adjustment and recently tested the cold start injector for leaks. Timing is set at 5 degrees with jumper in place. I have not had Check light flash while driving and there is no real problem with acceleration or driving steady speeds.

Besides vacuum leaks, can EGR valve cause this? Any other suggestions would be appreciated.

ffryno13

if it is an egr valve problem then which i had i and it threw a code on my check engine light it was code 71 i am pretty sure( which is the EGR malfunction). i took some carb cleaner and a 9" section of bailing wire and cleaned it out. let the carb cleaner set over night and clean the lines the best you can. hope it helps

Mikezord

Update:

I started my truck up yesterday and let it sit at idle to warm it up. About 15 minutes later I came outside to it idling around 1600 still, so I gave it a shot of throttle and it went back to the same high idle, and then started to do the rev thing again. So I opened the hood, adjusted the idle screw til I got the truck idling reliably at about 750, and the reving problem went away!

However, since my truck is sitting in the driveway with a broken control arm, I have yet to see how much of a solution this really is. I started it up again today and it didn't have any problems with the idle at any engine temperature.

Anyone know of a good place to find 4WD control arms? I'm not having ANY luck on all the major auto parts websites.

jesse j

im having the same problem but only when its on start up or 10 mins after i shut it off and started it again,i just installed an open cone filter so i figured it might be the maf but it wasnt moving in relation to the idle up and down .i had it idling up and down again so i ran and grabbed my test light to see if it was my fuel pump but i was getting a steady light ,i took the intake off at work and steamed it out with my high pressure truck,throttle body aswell,changed injectors,filtyers,plugs,im stumped if feels like it looses fuel pressure help any one oh ya when it is warm it runs at 750 and 1100 cold

Mikezord

Jesse, check your engine coolant level. I found that this problem went away once I made sure my engine coolant was topped up. I'm not sure how the two are related, but it seemed like they were. I had a leaky hose for a while and once my truck started acting up, I'd top it up and it went away.. so give that a shot.