400orBust

I'm out of ideas so need some help....here is the history. 1989 1st gen 4runner with 22re, manual, 116k original miles...original everything mechanical wise. Never any mechanical issues with it.
3 days ago when starting in the morning it fired then died but fired back up and was fine. Seemed odd but I didn't think anything of it. Did it again the next day but, again, started fine after initial failure. I drove about 15 minutes got gas, drove another 15 minutes, parked it and when tried to start it wouldn't. Cranks fine and after cursory check and more cranking it would fire on 1 or 2 cylinders...had it towed home. Got home checked a few things, air cleaner was filthy, changed that and it ran...barely. Tough to keep it running and doesn't idle well.

So this is what I've checked/done...
new air filter
sparks plugs good/fairly new
new plug wires and high tension cable
checked for spark
checked timing...5 deg btdc @750 rpm
Fuel pump is working
Fuel filter new 5000 miles ago
removed, cleaned throttle body, aux air valve
checked throttle dashpot and stop
new throttle position sensor set up (according to 4crawler.com)
cleaned battery posts and body and engine grounds
checked for vacuum leaks...can't find any
resistance tested cold start injector...within specs
tested afm...all in spec except resistance does jump above 1000 briefly while opening the vane
No engine codes at all

As of now it starts hard...have to really play the accelerator and try to get/keep rpms on it. Once it warms up it smooths out and I can let off the gas. Once warm it idles around 1000 rpm..occasionally trys to drop down but it won't. Even after warms it isn't smooth like it used to be.

Other things...
Have some major exhaust leaks
Haven't tested fuel pressure
dash temp gauge is erratic

So my thoughts are:
1)maybe faulty cold start injector?...but even after plenty warm it still idles high and runs sorta rough
2) aux. air valve wasn't plugged but I cleaned it anyways..the thermostat plunger moved when held under cold/warm water...there were no specs on how far to screw the disk/valve seat thing in so I got it hot and screwed it in till the valve was closed maybe could be off on that but again...even after warm still idles high and runs sorta rough
3) when jumping T and E1 it doesn't drop down to 750 rpms....it did yesterday but not today for some reason?
4) bad coil? but why would it run at all
5) does ecu take a temp input from somewhere? Dash temp gauge erratic but don't think that is connected to ecu is it?

I'm really at a loss here...I can't figure out why it happened so suddenly. I feel like it is an ecu/efi issue.
Any thoughts?

Thanks,
Jeremy

Co_94_PU

iTrader: (-1)

ECT sensor feeds the computer the engine coolant temp(located under the upper radiator hose), the dash temp gauge is a different sensor(located in the center of the intake tubes). The cold start time switch is located right next to the ECT.

Might want to try burping the coolant system.(some more?)

The air valve adjustment is "just slightly open at 68 degrees". The cold idle is 2 or 3k, go with 2 since I can't find the documentation for it best to be conservative. One of those two (Slightly open @68, or 2k cold) should put you back near 750 warm w/o having to adjust the idle screw.

Compression check, power balance tests? Might want to consider a new/used AFM, or try cleaning it but odds are it's rubbed off the conductive strip unless your seal has been broken.

Gizler00

iTrader: (1)

Maybe try another tps. And x2 on another afm. I have a few laying around. I could test them and if one is good, I could send it to you to try.

Let me know.

400orBust

Thanks for the responses. Here is where I'm at now...
Tested resistance on ECT and cold start time switch...both within specs.
Tested coil resistance...within specs
Installed new distributor cap and rotor
Tried to burp coolant system

After doing these and everything in my original post it does seem to run smoother but it still starts then dies, starts, then dies.
However I tried jumping Fb and B in the diagnostic plug and I can hear fuel going through the pressure bypass and when I start it with Fp and B jumped it does stay running longer and seems to be smooth...runs for about 10 seconds as opposed to 2 seconds without it jumped.
If I can get it above 2000-2500 rpm it runs fine...but if I tried to let down to idle it will try to run then die.

What does this indicate? Fuel pressure regulator, maybe fuel filter (only 1 year old), fuel pump working but worn out, or AFM?

I tested the circuit opening relay that runs the fuel pump from the key 'ON' position and the AFM...it seemed to be fine.

Gizler00...I may take you up on that AFM.

400orBust

I retested the AFM with assistance to hold the probes steady on the tabs and it was all in spec this time. By manually manipulating the AFM vane I can keep it running for quite awhile. What does this mean?

Co_94_PU

iTrader: (-1)

Definately check the fuel pressure. Opening the AFM vane will lengthen the injector pulses, so it gets more fuel. That follows along with better results when you jumpered the fuel pump power. Having to change your fuel filter indicates possible problems with rust or varnish in the tank and lines.

Think

This is a possibility: I had a similar problem where my 88 pickup would start and as soon as it got warm would throw up a check engine light and die. I'd start it back up and would run really rough for a minute with me giving it lots of gas to try to keep it going and then die.... Ended up being the pre catalytic O2 sensor was bad. Replaced and runs like new. If your exhaust system is old or has leaks this maybe worth looking at. I couldn't believe the O2 sensor could cause such havoc, but it was the culprit in my situation. Just a thought.

400orBust

I'll check fuel pressure and O2 sensor tomorrow. My exhaust system is really bad, pretty big leaks near muffler and a large leak in the compartment between header and exhaust pipe.

Co_94_PU

iTrader: (-1)

Checking the oxygen sensor is not going to do you much good, you need to fix the exhaust leaks first atleast upto the sensor.

400orBust

Fuel pressure with Fp and +B jumpered reads 46 psi...spec range is 38-44
Fuel pressure with engine running at idle (as best I could) and vacuum sensing hose
disconnected from pressure regulator reads 46.5...spec range again 38-44
Fuel pressure with engine at idle and pressure regulator connected reads 36.5 psi...spec
range is 33-37

This was with a new harbor freight fuel pressure tester so take that for what it is as far as accuracy but would being 2 psi high potentially cause these problems?

Also, if I understand the auxiliary air valve correctly... if the engine is warmed up it should die if I screw the idle adjust screw all the way down correct? If it doesn't die that means the aux air valve is still open even though the engine is warm right?

400orBust

Fuel pressure regulator I think. Seems to be running great now. See how it starts cold in the morning. Thanks for help everyone. I'll update if I have trouble in the morning.

400orBust

Well...no dice! It was running beautifully yesterday afternoon I thought I had it fixed. Went out this morning and it is not fixed. Same thing starts then dies, starts then dies.
Thinking about it I feel like it is a fuel delivery issue, I have pressure and the cold start injector works cause it fires right up cold...just won't stay running. I removed the cold start injector plug and hot-wired it directly to the battery. With my son starting it I can keep it running indefinitely by just giving the cold start injector battery power every few seconds. So that means injector problem right? I listened to all 4 injectors with mechanic stethoscope and all 4 are clicking away so could they all be plugged? But why would it run so well yesterday afternoon?

400orBust

Thoughts anyone??

400orBust

To update in case it helps anyone else...it was the ECM. I went through and tested everything possible. Finally started testing the ECM per factory service manual...the throttle position sensor parts of the ECM were way out of spec so I figured it was either the wire harness or ECM. I figured the ECMs don't go bad so I continuity tested the wire harness but it was fine. Finally, I found a correct ECM, plugged it in and it has run like a champ for the past week. Glad that is done.

Gargoyle_Runner

I'm having a similar issue but it's not the ECU/ECM. I have an 86 SR5 4Runner with 215,XXX on the odometer but don't know how accurate that is. I bought the rig last Feb from the PO who bought the truck in Cali sometime in the 90's. It is fairly clean and hasn't been abused but has been neglected. I have been working on it ever since. I finally got it to a point were it would start without a problem and purr like a kitten. It and gets, was getting, 24mpg around town. Then about two weeks ago I was driving and I noticed the idle started acting erratic. If I put my foot on the pedal it was fine. Went to the store turned it off and it started but continued to struggle and then would die if I wasn't on the pedal. I got it home and jumped the diagnostic plug and it gave me a 6 count which points to a few possibilities. It has a brand new cap and rotor, plugs and wires. Just for the sake of it I did a spray bottle test on the plug wires(they are Autozone) and there was no sparking or crackling. For an unknown reason I shot some B-12 intake cleaner into it and popped the positive off the battery to reset the codes. It started up and no longer is giving me a 6 count but instead giving me an 11 count. The TPS was new but I went ahead and tested it per 4crawler, what a great resource by the way. It was on the hairy edge of not good so I swapped it out with another new one and set that one perfectly - still 11. It's getting harder to start and less likely to run even with my foot on the pedal. So I then checked the resistance readings on the TPS from the connector that plugs into the ECU and am getting the same results that I did at the TPS so I know the wiring from A-B is good. I then checked the voltage at the EFI fuse and the resistance of the wiring from there to the ECU and it all checks out. At this point it will only start if I spray intake cleaner in and rev the motor over 2K, and it's not happy while doing that. Because it starts right up with the intake cleaner it seems like a fuel issue. For the simple sake of it I pull the idle air control valve off and check it - clean as can be and operates as it should. I pull the EGR and clean and verify it's operation, all good. I found an ECU for a good price and figured if it wasn't the problem it wouldn't hurt to have a spare. Swapped the ECU and no change, still 11. Checked the circuit open relay, working perfectly. When it was running I did run 2 tanks worth of B-12 fuel additive through and wondered about possibly filling the new fuel filter with gunk so I replaced it again. Pulled the fuel pump and checked the sock/filter on it as well as looked around inside the tank both of which were super clean. Now it will only start with intake cleaner and won't run for more than 20-30 seconds no matter what I do. When trying to start it I can smell gas but haven't tested the pressure on the pump. The timing is/was good. I have recently replaced the head, timing chain and adjusted valves so that stuff should all be good. I haven't messed with the AFM due to the fact that I haven't been given any codes for that.

Any clues anybody? Thanks for taking the time to read through it if nothing else, sorry it's so long

400orBust

I would test the AFM...I don't remember exactly how now but when I had all my problems I figured a way to test it using a multimeter and measuring the tabs on the plug. I think 4crawler has that test to and it is also in the FSM (factory service manual). That would eliminate that possibility. I think it is tough to diagnose these issues without being there...I got several responses when I had all my problems but really it is something you'll have to work through. Don't be surprised if it is the computer....mine also would run for a few seconds is all. I know I had fuel, spark and air....had to be a wiring or computer problem. If you have a FSM there is a procedure to test the ecm in there. Also, to see if it is a fuel delivery problem you can jumper the cold start relay. With someone cranking the 4runner to start it I was able to keep mine running by jumping that relay...eliminated a few things for me (and gave me the peace of mind KNOWING that yes...the motor still was good 'cause I was getting very frustrated!)

Gargoyle_Runner

So the problem was right under my nose, literally. The PO replaced the OEM radiator with something "similar". Well the upper coolant hose sits a tad bit lower than stock I've come to realize. I have also come to realize why the PO had the rigid intake tube that runs along the backside of the radiator mashed up into the coolant hose. There is no clearance between the intake tube and the fan blade. When I installed a new head recently I choose not to mash the tube and hose together and as a result the fan scrapped a hole into the bottom of that tube. I had inspected that tube before all of this when I did the head replacement so I didn't think to check it again. Throughout my troubleshooting adventure with this recent problem I never completely removed that tube just pulled off the end I was working around. I was just about to pull the injectors when I removed that tube and flipped it over and low an behold a 3 inch hole. It all made sense suddenly. Why the problem was progressively getting worse. Why I was getting an error code 11. Why it would only start with intake cleaner being sprayed into it.

Good news is I've now checked/replaced most of the relays, sensors, and valves as well as picked up a spare ECU.