LSUh20fowler

Need help guys. 1991 22re, has been running fine. This morning, while warming engine up, idle would surge after to operating temp. Went to the woods and hunted. Cranked cold truck, idle very rough like it had a miss. Idleing at 1500 after warmed up, but not surging. Press brake, idle surges from 700 to 1500. After sitting idleing, can see unburnt fuel from exhaust. Checked fire at each plug, it's good, oil level is good. Any ideas please help.

kornhuskerwizard

is your check eng light on?? good fuel in tank??have you checked your cap and rotor?? unburnt fuel means possibly not getting spark. check the simple stuff first

GrandPrix

I have researched idle issues a bit and this same brake/idle issue comes up often. I have yet to see a definitive cure to the problem. My 92 intermittently has the same problem but it is a manual so I just get off the brake at a level stop.

LSUh20fowler

Fuel is good, looked at rotor and cap look good. Changed the water temp sensor. Plugs and wires are firing and clean. I'm thinking maybe my TPS ?

blazer4513

I'm having the same problem with my 88 4runner, I changed plugs and wires because it needed to be done anyways, still no change. I haven't been able to tinker with it though because I've been in Georgia for a month.

GrandPrix

Mine still does the weird surge but only when on the brake and A/C on. Ideas?

SPARKS89

iTrader: (1)

Sounds like vacuum issues. Unhook the vacuum line from the brake booster and plug the end of it. Start the truck and see if the idle is still acting funny.

Co_94_PU

iTrader: (-1)

My surging was the fuel cut off kicking in. Make sure you use an accurate tach when setting the idle. The AC Idle up should add about 150-250 rpms (900-1000).

Is it a racing surge or bogging surge?

GrandPrix

Pulled the brake booster hose and plugged it. Engine idled fine with both A/C on and off. No surging when I pressed the brake pedal. Reconnected the brake hose and was just as good.
This is so frustrating. Only surges when I drive it with A/C on and press the brake pedal. No A/C no surge.

FirstGen4x4

I would check for a hole/crack in the intake after your mass airflow sensor.

GrandPrix

No because the air intake set is new and no leaks were detected. Thanks.

GrandPrix

Idle only surges while AC is on and pressing on the brake pedal.

Cmayer

Try adjusting you're AC Idle Up down a little bit to get your idle around 900-1000 rpm.

If your idle is too high the fuel will cut out when you step on the brakes. It will rev, fall, rev, fall ect.

I'd check for vacuum leaks, air leaks, and then make sure idle without AC is set right, and that idle with AC on is set right.

RylerTust

make sure your coolant is topped off. ive heard that can cause the idle on these engines. i had a similar problem after i cleaned my TB. get TB cleaner and spray all vacuum lines, see if you have a leak anywhere. no CEL? to test TPS, act as if checking timing, if you short the connection in the diagnose port and the idle doesnt change, tps can be bad, back up this hypothesis by checking tps with a volt meter. clean tb and readjust idle to what is specified on catalyst. 750rpm i believe. turn on ac and adjust the idle up to ~1000rpm. clean MAF sensor. the surge/lope is cause these engines will cut fuel if it sees increasing idle while the brake is applied. my problem was the PO of the truck adjusted the idle without cleaning the tb or airfilter. so after i did both it got a little more breath, and idle increased. hope some of this helps. good luck

Co_94_PU

iTrader: (-1)

Drive it if you need to replicate the symptom.

In no particular order..

Test the booster for leaks, (FSM page BR-7)..
Replace the hose first (it's cheap), make sure the attachment points are clean and free from stuck on rubber bits also. and/or replace the leaking the booster.

Test for fuel cut off triggering, by jumpering B+ and FP in the DLC.

If this solves the problem. Verify the normal idle is set to 750 or 850(for 4wd Automatics), and verify the AC Idle is 900 or 1000(for 4wd Auto). After verifing the idles are set and the problem still occurs, test the AFM (EG1-194) and Circuit opening relay (EG1-207).

It could be "really bad". Low oil pressure and or flow causing bearings to bind at low rpms.

Check oil level and condition. Replace oil filter. Pull the pan and clean the pickup screen. Attach an oil pressure gauge, analog type with PSI/Kpa type readings.

Abnormally high pressure may indicate blocked passages.

Abnormally low indicates a failing pump or stuck pressure relief. (Both require a new pump, or creative engineering)

Co_94_PU

iTrader: (-1)

Now regarding the OP's symptoms

It idles like it is cold when it is warmed up.

Might be a stuck vac switch (or two), clean the filters and verify they all open and close properly.

You may have a leaking injector, a cleaning might help but they also might need rebuilt or replaced.

Probably best to start with an AFM test before you go to pulling the injectors off.

iworkalone

Having idle problems myself, 1987 4runner, 22RE. I changed my pressure regulator & made HUGE difference. Still unable to get idle down to proper setting but I know I have timing issues. Good luck. FYI, I got my regulator from autozone, entered special promo code that is posted on their website & saved $20 w/ free shipping.

RylerTust

May be a dumb question. TB clean? Air filter clean? Any leaks in any vacuum passages/lines? Idle screw o-Ring may be bad?

Ugly4Runner

I would wager that the liquid you are seeing coming out of the tail pipe, especially if it's a cold morning, is water vapor that condenses on the inside of the cold tailpipe, not unburnt fuel. I had a similar surging issue which turned out to be a fuel cutoff situation. The idle air screw was WAY out of adjustment, too open, and the coolant passage on the iacv was clogged so it wouldn't close. Good luck!