KYLEFOO

Edit:it won't idle smooth below 1000, hot or cold. If I lower idle speed, it won't start without throttle.

I bought a built 87 4runner last may and have had nothing but problems with it since. It is a federal model and has 202000 miles, 35"s, 5.29, sas. (I'm in CA) I drove it for about a week before I found out that it had rust in the gas tank and low compression so I took the block to a machinist (Performance Engines of Sacramento) and had him rebuild the short block with .020 over pistons and I installed a new ITM head. I replaced the gas tank, fuel pump, had Injectors serviced (Dr. Injector of Sacramento) and flushed the fuel lines with fresh gas.

I have it running now but the idle is weak, which was a known problem when I bought it. If I set the idle at 750 it idles rough. Once it is warmed up it wont start without throttle if Idle is set at 750. Otherwise it seems ok if I keep the idle above 900. I drove it up to the mountains and it makes decent power considering the tires/gears. It seems like a vacuum leak but I have picked over the vacuum/intake hoses (made repairs) and sprayed carb cleaner on the intake around the gaskets. I have another 4runner same year that I have been swapping parts with. Even though the truck is a fed. it appears to be the same under the hood as my california model.

I have tried:

• Base timing
• valve lash
• Ignition timing 5 degrees BTDC
• Check for vacuum leaks at hoses and intake gaskets
• Block the EGR at the plenum gasket with aluminum can shim
• Burped air bubbles from cooling system
• Swapped Idle air control valve
• Swapped igniter/coil
• Swapped distributor
• Swapped AFM
• Swapped TPS
• Tested ignition with Snap-On digital reader
• Tested Voltages at ECU
• Tested solenoid resistor, both 3 ohms
• Tested main relay, 72ohm between 1&2 open between 3&4
• Tested compression, 140, 140, 145, 150
• Tested AFM
• Tested TPS, idle drops to set correct ignition timing
• Tested fuel pressure, 36psi w/oreilly gauge..
• New Denso O2 sensor (made idle worse)
• New spark plugs BPR5EY .031
• New wires, cap and rotor
• New Coolant temp. sensor

I must admit my shame, this majestic beast has been damned to the confines of my driveway for almost a year now. I thought that I was a pretty good mech. but this one is giving me hell. Please help me get it running right for a summer of wheeling!!!

KYLEFOO

I tested fuel pressure today which was at 36 psi. This seems like reasonable variance. I dont imagine that low fuel pressure would only give me a weak idle.

Also, when I was triple checking the ignition timing sunday I noticed that if I advanced timing to 10+ degrees btdc the idle would smooth out.

KYLEFOO

BUMP Im poking at the 4runner this afternoon, checking coolant temp. sensor again and trying the old carb cleaner trick again. Im still not seeing any problems. I'm going to check compression after the engine cools.

Compression was 140, 140, 145, 150. That seems a little low and the plugs were a little ashy on the tip and black around the ring.



Does anyone have ideas that I can try?

SoCal4Running

When I rebuilt my 22RE I had used the wrong Throttle Body Gasket.
There were 2 in the kit and simply didn't notice the difference.

Idled like garbage.

I didnt find it until I got a small bottle of propane and starting sticking the nozzle in the nooks and crannies. Carb cleaner didnt do it because the gasket is only open on the bottom of the TB and the fluid couldn't get in there.

KYLEFOO

Thanks for the ideas socal, I already tried to check for leaks with propane but moved to carb cleaner to hit those hard to reach places. I took the TB off to swap the TPS and found that I had installed the tb gasket backwards. I corrected this and rechecked with propane.

Today I retested coolant temp sensor and updated readings in my first post and swapped/ adjusted TPS. I also listed readings for solenoid resistor and main relay. The weak idle remains.

KYLEFOO

I'm poking around at the 4runner again today. I swapped igniter/coil, the tube between the air filter and TB. Then with the engine running, I poured water over the intake and still no signs of a vacuum leak. Im going to start testing wires at the ecu. Anyone with ideas which have not been tried please give advice.

KYLEFOO

I finished performing the voltage tests at the ECU tonight. the results were:

• +B-E1, key on, spec. 10-14v, meas. 11.88v
• BATT-E1, spec. 10-14v, meas. 11.90v
• IDL-E2, key on, throttle open, spec. 4-10v, meas. 10.96v
• VTA-E2, key on, throttle fully open, spec. 4-5v, meas. 3.56v
• VTA-E2, key on, throttle fully closed, spec. 0.1-1.0v, meas. 0.43v
• VCC-E2, key on, spec. 4-6v, meas. 5.0v
• IGT-E1, idle, spec. 0.70-1.0v, meas. 0.70v
• NO.10-E1, key on, spec. 9-14v, meas. 11.96v
• NO.20-E1, key on, spec. 9-14v, meas. 11.91v
• W-E1, idle, spec. 8-14v, meas. 13.98v
• VC-E2, key on, spec. 4-9v, meas. 7.74v
• VS-E2, key on, plate closed, spec. 0.5-2.5v, meas. 2.98v
• VS-E2, key on, plate open, spec. 5-8v, meas. 7.22v
• VS-E2, idle, spec. 2.5-5.5v, meas. 4.80v
• THA-E2, key on, spec. 2-6v, meas. 2.71v
• THW-E2, key on, hot 176*, spec. 0.5-2.5v, meas. 0.43v

I guess this is a good time to mention that it looks like the engine caught on fire near the fuel rail at some point. The check connector is not wired in and the harness has probably been messed with. I have no trouble codes but the dtc system does appear to work. If for instance, I unplug the TPS or coolant temp sensor, I get a code. Also, the alternator had a bad regulator which I didnt notice because the light didnt come on unless I was cruising at 2k rpm for a couple min. Fixed during rebuild... I see that the voltages of numerous circuits are out of spec, could the wire harness or most of the sensors get fried from a failed voltage regulator? Remember, I'm not getting trouble codes..

KYLEFOO

We adjusted valve lash, which helped some. We also tested spark with my buddys digital reader that lets you look at voltage peaks in fractions of a second, my ignition is golden. We were unable to figure out why it wont idle right and ended up setting the idle at 900. It idles fairly smooth there and starts ok most of the time. I'm still looking to figure out why the idle is "weak".

KYLEFOO

I went ahead and replaced the engine coolant temp sensor based on my buddys suggestion. It still wont start or stalls unless the idle is set above 1000 rpm.

KYLEFOO

BUMP it needs a smog check to register this time around and idle is still out of spec. Does anyone have input?

KYLEFOO

I'm doing the sensor tests at the ecu to test the wire harness.

Coolant Temp Sensor

• THA-E2 = .29 Kohms, within spec.

Throttle Position Sensor

• VTA-E2 = .76 Kohms, throttle closed, within spec.
• IDL-E2 = .50 Kohms, throttle .022", within spec.
• IDL-E2 = open, throttle .033", within spec.
• VTA-E2 = 5.19 Kohms, throttle fully open, within spec.
• VCC-E2 = 6.68 Kohms, throttle closed, within spec.

Air Flow Meter

• VS-E2 = .07 Kohms, within spec.
• VC-E2 = .18 Kohms, within spec.
• VB-E2 = N/A, no pin at ecu?
• THA-E2 = 1.42 Kohms, within spec.
• FC-E1 = N/A, no pin at ecu?