HawkStrong16

Hello, I'm new here, been lurking about for a while trying to find answers as to why my truck is running so bad.

My '90 22RE 5spd has been running pretty rough at idle for about three months(ish) ever since it got cold out
When first started it will sit and idle normal, then once it starts to warm a bit it will bog down then even out, bog down even out etc, it will only due this at an idle, also when I hit the brake pedal it drops the engine RPM down(I don't have a tach so I have no idea what I'm at) and does the same thing.
I thought it was a vacuum leak but have been unable to find it.

Also while driving whenever I shift it will rev when I hit the clutch, then go back to normal. I am also suspecting the TPS(throttle position sensor)
However I do not know where/how to test the TPS. So if someone could tell me where the TPS is that would be awesome(pics would be great)

I had an oil test done and they told me I had very trace amounts of antifreze in the oil, and after noticing I was a little low on coolant I added BarsLeaks Head Gasket Fix, that worked on my neighbors 350, so I thought I'd try it, it seems to have fixed the losing coolant part anyway.

But if anyone could help with my idle problem it would be great. I'll try to take a video of it idleing poorly to help you all help find my problem

AmpedRunner

If your rpms drop when you hit the brakes (with the clutch in or in neutral I'm assuming) You should check your brake booster for vacuum leaks. A vacuum leak in your brake booster can cause idle issues and will cause your idle to fluctuate when you hit the brakes.

As for the TPS here is where it is on the right side of the throttle body



here it is off the engine


Here is the electrical diagram


As for the coolant leak, unless absolutely necessary, it's generally not a good idea to use stop leak as it will plug your radiator and heater core. which makes a mess Coolant in oil could mean your head gasket is starting to go or your timing chain has cut through the timing cover. Both of which should be looked into asap.

Hope this helps!

HawkStrong16

I'll look in to my brake booster, asap, unfortunately it is my daily driver and I wont be able to check my head gasket/timing cover until June(when I graduate) so until then its frequent oil changes with a good filter, I made sure to flush my cooling system before I added the stop leak. And I'll either do the work, or drive it till it blows and swap in a Diesel(as I am in school for Diesel tech)

toyota4x4907

Like already said, stop leak is CRAP!
Sounds like you do have a head gasket leaking...or the timing chain ate through the cover. Either is easy to check.
Take out the spark plugs, if one or all are really clean, and/or wet on the threads or other areas, then coolant is probably getting into the cylinder. And/or look into the spark plug holes, see if you can notice if one or all/any of the cylinders are clean looking. Mostly you will be looking for the tops of the pistons.

Taking the valve cover off is EASY. just a few bolts here and there. Look on the driver's side of the timing cover to see if there are chain marks and/or holes. And look to see if either of the chain guides are busted.

The idle problem actually probably IS NOT due to the brake booster. Those rarely fail. It most likely has to do with coolant being low and/or air in the cooling system and/or TPS. But since you are losing coolant, the first two are most likely. Also, make sure the idle is set BELOW 1000 rpm. if idle is set at or above 1000 rpm, and step on the brakes, the engine will surge.

Good luck

AmpedRunner

If it is your timing chain wearing through the cover then this is what is happening
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Very bad, and if it's not fixed then your coolant will mix with your oil and destroy your bearings. Same thing will happen if the head gasket fails, though it will be more noticeable because your engine will smoke.

What kind of diesel are you planning on swapping in?

HawkStrong16

I actually just checked my spark plugs and they all looked fine, I replaced them about 6000 miles ago. they look normal to me.

If all I have to do to check the timing chain cover is pull the valve cover then I'll do that this weekend and post back what I find, I'll also do a more extensive check of my cooling system, but I appear to have stopped losing coolant since I added the Head Gasket Fix.

How do I go about checking my TPS?

I haven't decided what diesel I want. I'm thinking of one of Toyota's L series, like a 2L-T. Since then I can use my tranny and engine mounts.

How hard is it to change the front cover, do I need to pull the head and or distributor?

AmpedRunner

Download a Full Service Manual here http://www.ncttora.com/fsm/index.html

It will tell you how to check the TPS and how to change the timing chain and cover if that is the problem. Plus it can help you diagnose most any issue you come across.

Toyota diesels are crazy expensive, but awesome. good luck!

HawkStrong16

Thanks for your help!
I'm really hoping I don't have to dump to much money in this engine, its got around 200,000 miles on it, I don't want it to nickel and dime me to death

AmpedRunner

Hey your welcome! glad to help. do you have any of the service records for the truck? If it's been 200,000 without much maintenance then their are probably lots of things that need to be checked. But if it has been well kept then after you solve your current issues it should be good for awhile.

Have a great evening!

HawkStrong16

I actually do have the service records, the guy that owned it before me was almost anal about keeping records on the truck(not that thats a bad thing, I've been the same since I bought it)

I'll have to go though them and see if it has ever had a head gasket/timing chain cover before

AmpedRunner

Good Idea, I wish I had records from my PO, would have made allot of things much easier. Good for you for keeping record it will serve you well in the long run

HawkStrong16

There was a new timing chain put on in Jan. of 04. At 136,000 miles. The truck has 195,000 on it now, and seeing as how I put 100+miles a day on it, I'll be at 200,000 in no time.

If it had a new timing chain put on would it also have had new dampers and a tensioner at the same time? Also do you have to remove the cylinder head too when you do this kind of work?

peckinpah

No, you don't have to remove the head to do the timing chain, just unbolt everything from the front of the engine (and I mean EVERYTHING) and remove the 18 or so bolts holding the timing chain cover in place.

Usually when the timing chain is done, the guides, sprockets and tensioner are also replaced. You only have less than 60k on he new chain, so I would not expect this to be the problem. A timing chain job usually lasts a good 100-120k.

Here is how you check the TPS. Pretty easy if you have an Ohm Tester and some spacers:

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

You might also take a look at your throttle body, and if it's really dirty, run some Seafoam thru your brake booster line and gas tank. Just don't get any throttle body cleaner on your TPS, because that can ruin the electronics in it. Good luck.

HawkStrong16

I'll be able to test my TPS tomorrow(I hope, pretty busy schedule)
I hope thats it seeing as how it should be a pretty easy fix, guess I'll find out in due time.


Luckily I found a 2000 Blazer that I'll be able to pick up cheap. 286,000 miles, it was an escort vehicle, so it was all pretty easy highway miles, it'll get me though the winter at least

toyota4x4907

Dude, have you checked your coolant level?

HawkStrong16

Yeah its been alright since I added the Head Gasket Fix. I'm about to do an oil change and get another oil report done to see what they say, but I need to get my idle figured out

deejaysterling

this could be a bad/stuck chain tensioner, that would explain when u speed up it is better but abrubt stopping/hard braking can stall/jump. the fact that your rev's go up when you hit the clutch is something different though..so maybe the TPS is also a good check. has the fuel filter ever been changed? fuel pump? good pressure?

HawkStrong16

How do you check fuel pressure?

I replaced the fuel filter in October of '09 when I got the truck, its one of the things I always do when I buy a used vehicle.

HawkStrong16

I've just noticed that after I fill my radiator, it will push a lot of coolant back out in to the overflow, down to where you can just see the top cooling fin. Any ideas?

Also, a friend of mine found a '94 truck just like mine, all it needs are new axles(which come with the truck) and tires(which I can take from my truck)
The guy wants 800$ for it he said it runs great, just needs those things for inspection. He wants it gone because he bought a '64 Nova. What do you guys think?

Heres the '94

peckinpah

Is the truck a V6? How many miles? Does it start up? And most important, do you have room for a partially dismantled truck in your driveway?

Re the coolant level, that's normal. As long as you aren't losing coolant, I would not worry about it.