91 4 Runner (6) - needs to warm up?

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Gusb

Gusb

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What could be going on with a 91 4 Runner that runs rough when it's cold and fine when it warms up?

Could it be some kind of coolant temp sensor/cold start injector?

It just passed California smog - but could still it be a leaky head gasket? How much trouble to replace a head gasket on this 6 cylinder?

Thanks,
Gus
 
There's also a search function on this site...


I wouldn't head on over to Yotatech for anything unless you like getting a reliable answer on or about every 8th post.

If you want it fixed, here's a good spot.

I've also noticed that posts that don't get a fast response are usually easy to find answers on the posters part...

At least we don't say SEARCH NooB! Like other sites... But it does get tiring to keep posting on rehashed items...

Something Yotatech has NO problems with...


The Toyota 3.0 V6 was introduced in 1988... It's now 2011... hint hint...

Things like "How hard is it to replace the gaskets?" should already have been covered...
 
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Tommy the Cat said:
I would head over to yotatech and search "cold start" or just "cold" in the 86-95 truck section. It's been covered very extensively.
Click to expand...

Thanks for the reply Tommy the Cat - I did find more info searching on yotatech (sometimes go there for my 1980 pickup). I spend most of my time here in the 40 section and I've never been called a "NooB" before (and it took 8 lines of copy to do it :grinpimp:) - think I'll run back to 40 Tech :D

Anyway - bought the 4 Runner (for my granddaughter). The thing seems to be in remarkable shape with 179K miles. Sun damage on the top surfaces but I've only found one small dent on the entire body, interior is in great shape, etc. etc. see attached.
chloe1.webp
 
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The 6 is a load of fun to work on, if nothing goes wrong you can change the head gaskets in 2-3 days (if it's your first time) Just remember, everything you can see on the engine has to come off.... plus plenty of stuff you can't see... :D They are fun trucks, I've owned plenty.... Hehe :cheers: Welcome to the dark side!
 
I love working on the 3.0


But I love smashing my thumbs with hammers, wasp attacks, kicks to the groin & drinking parts cleaner
 
2ndGenToyotaFan said:
Just remember, everything you can see on the engine has to come off.... plus plenty of stuff you can't see... :D
Click to expand...

Tip: Take lots of photos as you pull stuff off. :cheers:
 
No worries Gus. I'm a 40 owner too, but my daily driver is a '90 pickup with a 3.0. It's not near as bad to work on as some will lead you to believe and is very reliable (though under-powered and gas-hoggish) once the head gaskets are taken care of. The 22RE is far easier to work on and just as reliable but I wouldn't trade my 3.slow for one and I've owned a bunch of both. I enjoy what little power it adds.

Anyhow I doubt head gaskets are your problem. More likely something like the coolant sensor (it does wacky stuff when it goes bad) or timing/tune-up stuff. Check for oil in the water, water in the oil, steam out the tailpipe etc. if you really suspect head gaskets, though.

Yotatech can be a pain sometimes but if you look long enough you WILL find good info. You just have to filter out the garbage.
 
Check that the cold start injector is getting power when the engine is cold. The engine temp sensors would be a good thing to check as Tommy suggested as well...

Check the FAQ thread for some links to FSM's There is a 93 4Runner manual in there you might find helpful. Not everything will be the same, but close enough to get you started... :cheers:
 
If you are having trouble getting it started the cold start system is the first place to look, however it only functions very briefly. As in during cranking. It has an internal heater that works off battery+ sent from the ignition switch only during cranking. Further enrichment is handled by the main injectors in open loop via info sent to the ECM by the oxygen sensor, coolant temp sensor, etc..

Here is the FSM link. Invaluable.
1993 Toyota Pickup Service Manual
 
Thanks for all the feedback - much appreciated.

At this point the thing seems to run well and I couldn't get a really clarified answer from the PO who somehow eliminated the rough cold idle problem. As I said before he also put the truck through CA smog with no trouble, threw two new shocks on the front, checked the brakes, etc. Who knows, he may have added some kind of sealant, etc. to the engine :eek:. He is a mechanic, was selling it for his neighbor and she had owned it forever ...

Anyway - my granddaughter has driven it around for the last few days and - touch wood - it seems to be OK at this point.

Gus
 
Tommy the Cat said:
If you are having trouble getting it started the cold start system is the first place to look, however it only functions very briefly. As in during cranking. It has an internal heater that works off battery+ sent from the ignition switch only during cranking. Further enrichment is handled by the main injectors in open loop via info sent to the ECM by the oxygen sensor, coolant temp sensor, etc..



Here is the FSM link. Invaluable.
1993 Toyota Pickup Service Manual
Click to expand...

no poop that is good chit to know, are the 22re's the same way?


sorry about the hijack!
 
Update - couple of times now the granddaughter has had problems starting the 4 Runner. Turn the key and nothing - but the battery still seems good. Not sure if there's a starter-solenoid type click but the engine does not turn over. Played with the key (off-on) and after a bit it hit and started. Could it be a short somewhere, the battery seems pretty robust?

I'm also searching the forum for clues... :)


There's also a noise (seems unrelated to the starting) that I always hear when the key is turned - engine running or not - that sounds like a little motor on a timer that runs in the passenger-side front engine area for about 10 sec.?
 
Not sure about your 10 second noise, but the starter relay is probably dirty. Check to see what voltage is getting to the small wire at the starter when the key is in the start position... Old wires and dirty contacts usually drop the voltage getting to the starter until there is not enough to kick the solinoid into gear, and all you get is a slight click of the relay... If you aren't even getting a click, then you might want to check the ignition switch...

Good luck! :cheers:
 
2ndGenToyotaFan said:
Not sure about your 10 second noise, but the starter relay is probably dirty. Check to see what voltage is getting to the small wire at the starter when the key is in the start position... Old wires and dirty contacts usually drop the voltage getting to the starter until there is not enough to kick the solinoid into gear, and all you get is a slight click of the relay... If you aren't even getting a click, then you might want to check the ignition switch...

Good luck! :cheers:
Click to expand...

Thanks a lot - I think the starter relay might be the problem. Checked voltage at the small wire and it was down around 7. I think I read somewhere it should be within .5 volts of the big wire? And I do get a light click and it does NOT seem to be the A/T transmission shift safety thing.

But where is the Starter Relay on this 1991, can't find it and it seems impossible to trace the small wire back from the starter. It's not anywhere on the passenger-side wall (or engine) I can see. Can't see it under the driver's side dash? It's not that relay in the engine fuse box, right? All I've got is an on-line 95 FSM for reference.

Gus
 
Starter relay (solenoid) is part of the starter. The small wire is the control wire. Check the solenoid's contacts. They may be burnt up and no longer making proper contact.
 
Bogo said:
Starter relay (solenoid) is part of the starter. The small wire is the control wire. Check the solenoid's contacts. They may be burnt up and no longer making proper contact.
Click to expand...

Im trying to find the Starter Relay - because I have low voltage at the solenoid ...

95 FSM shows this (see attached) in the engine main fuse box. Toyota part printouts show other locations - I can't find mine.
starter_relay1.webp
starter_relay2.webp
 
Ah, OK, that starter relay.

The 93 FSM says it is in the same place. Both my '94 and '95 have it in that spot. I wonder if somebody bypassed it? Hum, where is it in an older 4runner? The 88 FSM has it attached to the fender wall up near the top. See the '88 FSM PDF in the FAQ thread. It shows it as being held to the fender with a bracket by it's lonesome. Wires off of it look like they disappear into the wiring harness. Somebody could have back reved it to the old design. The other possibility is they still had old parts at the factory and were getting rid of them. Is yours an early production model?
 
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