boontok

Greetings everyone! I have a unique problem with my 1987 4Runner (22RE engine) that should be simple enough for one of you to diagnose, but it's a bit complex for this backyard mechanic. My mechanic couldn't find the solution without charging me for at least my arm. I am going to give you the condensed facts rather than telling you a story of how the problem came about and my attempts to fix it.

Problems:

• The truck jolts and stutters upon acceleration almost completely lacking power.
• Once tachometer reached 2800 RPM the engine surges (like a turbo spooled up) and runs normal above 2800 RPM.
• backfires while decelerating
• idles low and will cut off most of the time if I don't hit the throttle
• as trouble starting again after engine is warmed up

Misc:

• cold starts great and runs fine until it's warmed up
• spark plugs look a bit white (lean air/fuel mixture?)

Conditions:

• When air temperature outside is below 55°F the problems are consistent.
  • It runs great from cold start for about 3-4 minutes and then the problems activate like a switch.
• When air temperature outside is above 55°F(but below 70°F - it's not been that warm yet):
  • truck takes a bit longer to reach it's problem state, but eventually it does
  • when I park the truck for a few minutes in idle the problem completely goes away and will drive great for about a mile or so and then comes back

Presumptions:

• Something on the truck does not like running at a cooler temperature, such as when it's a cold day or when air is blowing by while driving on warmer days.
• coolant/water temperature sensor?
• ignition coil?

Attempts:

• replaced O2 sensor
• checked for vacuum leaks (sprayed starting fluid around gaskets and hoses to see if engine would surge)
• new fuel pressure regulator
• new gaskets on intake
• swapped mass air flow (MAF) package
• replaced air filter
• replaced throttle position sensor (TPS) and adjusted to service manual specs
• timing is correct
• plugged off EGR
• swapped ECU
• new injectors and seals

I really appreciate your help.

olharleyman

fuel filter , fuel delivery/pump have you checked/changed them?

boontok

Yes. Both of those.

olharleyman

cat? muffler?

boontok

I wish.

abecedarian

I'm wondering how you can set the timing correctly since the timing is dependent on idle speed and you say it idles low, to the point of dying...? If you set the timing with the idle that low, your timing is significantly over-advanced.

Anyhow...
Any exhaust leaks? Valves set properly (.008 intake / .012 exhaust with warmed engine)?

boontok

The problem goes away after a few minutes when I park the truck. That's when I set the idle. No exhaust leaks and valves are proper. Thanks.

4runnerx3

Have you checked the distributor cap for cracks? Did you spray fluid around the bottom of the injectors?

sas'd22re

having the same problems with my 86 22re as well. tps and afm checked out fine, 02 sensr could be bad and im checking the timing on monday at a friends shop. could either the 02 sensor or the timing cause our problems?

abecedarian

the O2 sensor is not used as a reference when the engine is at idle or wide open throttle... IF the TPS is set properly.

sas'd22re

how about hesitation and sputtering upon accelerating?
edit: forgot to mention that i currently disconnected my o2 sensor to see if it made any difference

abecedarian

I'd check the plugs (heat range and gap) and coil, and that the afm vane moves smoothly and there are no vacuum leaks (including leaks in the duct from the throttle to the afm) as well as double/triple/quadruple checking the timing.
otherwise you're stuck with an injector or valve issue, or possibly the EGR operating when it shouldn't.

sas'd22re

ok thanks. ive swapped out an egr valve and IAC valve, with no change. i have a spare coil and igniter so ill swap those in tomorrow and see if anything changes. also sputtering/hesitation is intermittent

boontok

4runnerx3: Yes to both, and this didn't help... thanks.

abecedarian: plugs good; I need to check the coil; afm vane is great; no vacuum leaks; timing has been triple checked; egr is not problem either

Here's a new discovery: When I turn the key on, the coolant temperature gauge on the dash goes half way up. Is this gauge driven by the coolant temperature sensor? If the CTS was giving a false hot reading, wouldn't the ECU be running a leaner fuel ratio (thinking that the engine is hot when it is actually cold) and also causing the coolant to circulate as soon as the engine starts, not allowing it to heat up properly? This makes sense being that the truck runs great when I let it idle for a bit (allowing it to build up heat in the engine bay). What do you think?

abecedarian

The gauge gets its reading from a sensor between #2 and #3 cylinders and the ECU gets it's input from a sensor on the front of the intake manifold. The two are not connected in any way that would make one influence the other- they are two different circuits.
HOWEVER, the fact the gauge reads high when turning the key on suggests there's a grounding or other wiring issue. Check the engine grounds from the block (near the engine mount), the intake manifold (behind the #2 intake runner), the rear of the head (to the firewall) and by the alternator and make sure they are all good.

Braden 87runner

Im expierencing the same exact problems, i know for a fact i have an exaust leak coming directly from the manifold im going to fix it soon but im not sure if the leak is related to the surging.

ive replaced the TPS and Checked the MAF both are operating properly.

any suggestions on what other basic things i should check?

oldtoyguy

Boontok, I read your post regarding your problem with the idle and temp sensitive problems on your truck. You EXACTLY described the cluster of syptoms Ive been fighting, and we have done virtually the same things to try and fix. I too have a pacesetter header, but i had the problems before installing it. I had resorted to "adjusting" the airflow meter to overall enrich the mix to make it driveable. IM at the point of looking at replacing the engine wiring harness, now that I know Im not the only one with these symptoms. It leads me to think there is a failure mode that is showing up with age and mileage. I am thinking of possibly a corroded wire or a splice that has created too much resistance. Alternately I wonder about water flow around the efi temp sensor as having something to do with the sensitivity to temp and the fact it clears after shut down and restart shortly after. Bottomline, I would be interested if you have had any luck. Maybe working together we can think this one out. Is IS wierd!!
Thanks

boontok

Yes, let's put our heads together!

I changed the coolant temp sensor, to no avail.

I am about to try changing the O2 sensor again.

yotahead87

mine had the exact problems, i changed the fuel filter and it seemed to stop the hard missing and stuttering. it was rippin around real good for a few days so i took it out wheelin today and got stuck in a deep water hole, started running like te again, changed the air filter got er out. and now its missing slightly again, as soon as i take it out of gear the motor will fall on its face unless i give it some gas. it takes off like a raped ape as soon as it touches 2700-2800 rpms.. that doesnt make any sence to me. i have a throttle body out of an 88 (mines an 85) i cleaned it today think thatd help the situation at all? in the dark i can see my ignition coil arcing around a bit, would this have anything to do with the miss?

oldtoyguy

Ive talked to Boontok and I have got my truck at a Toyota Guru friend who used to do tech work for the Factory. He thinks it might be a wiring harness related problem, but I will pass along the observation about the arcing coil. It could be a common factor also. I have not changed my coil or igniter, I dont think Boontok has either but I will check. I will post here as soon as my friend comes up with a solution so we can all benefit. Hang in, this guy is really good, so Im hopeful for a solution.