Aerodude180

Hey everyone, having some trouble with my 87'
I have a 1987 4Runner, 22re Fuel Injected, 5 speed manual, non-turbo.

After running fine all morning, I took off down the road is it started running terrible, engine bogging down and cutting out, vibrating, barley able to keep going even at full throttle - till it died on the side of the road and I couldn't restart.

Since then I've been able to get it to start and run for about 10 seconds, maybe a little longer if I tap on the gas pedal but then it sputters out and dies.


• Pulled each spark wire to test for spark
•˟checked all fuses - put new fuses in EFI and Ignition to be sure
• I tested the TPS with an Ohm meter - withing specs (fairly new TPS)
• I've tried running with the fuel pump jumpered between B+ and Fp in the diagnostic port - no luck. I can hear the fuel pump running with it jumpered.

•˟I hear relay click and fuel pump run when I push open the door on the Air Flow Meter

• Jumper in the diagnostic port for check engine light gives me Code 28 - Oxygen sensor

After trying everything else I could think of - I've discovered that if I stick something in the Air flow meter to hold the door open I can get it to continue running non stop. Not well, some white smoke out the exhaust but it runs. Thats how I got her home.

Prior to this I was having an issue with the alternator/voltage regular where the voltage meter would jump up to +18v...wondering if it could be related.

Any thought or Ideas?

lonfu

sounds like MAF is bad to me! If it is sooted up you can try to clean it, but..... you could have a vacum leak too! check the rubber boots to make sure. I had one on the under side and couldn't see it until I removed it. PIA

scope103

It still sounds like a VAF/COR problem. The FP-B+ jumper you described IS the way to diagnose that, so you might re-run that test.

You could have a VAF vane so stuck that it just won't open; you should be able to idle with that, but it won't accelerate (at least when cold, in open loop). Or you could have a dead-spot on the in-VAF rheostat. Try testing the VAF: http://personal.utulsa.edu/~nathan-b...33volumeai.pdf (this manual is for a '93, but it usually works. But check the number of pins; there is some variability.)

skypilot

iTrader: (1)

I think your plenum is open to the outside. VAFM has a micro switch for the fuel pump in it. It don't take much to keep it open and the fuel pump running. I think you really need to inspect the plumbing. Putting a stick in the VAFM proves the pump works. Now white smoke is probably the head gasket. Check your oil for a milkshake and bubbles in the radiator.

+18, maybe you smoked the ECU without realizing it.

Aerodude180

Thanks everyone - I tested the VAFM with an ohm meter as specified. Passed all static and dynamic test - only exception was the final test E2-Vs sometimes hit as high as 2500ohms. (upper limit of the spec is 1000)

I pulled all the plumbing off for inspection - no cracks or openings.

Is it possible the ECU is shot? and recommendations to diagnose that? other than swap in a working one?

TipsyFox

Have you checked the timing yet? Maybe it jumped a sprocket on the chain and knocked the timing off.

Aerodude180

I got another, known good ECU and swapped it in - no luck.

- Will checking the timing with a timing light let me know if the chain jumped a sprocket tooth or do I need to dig deeper?

Distributor pick up?

scope103

If the CAM timing is off, you should have low compression (the valves aren't opening at the right time vis-a-vis TDC). A timing light won't show that; it just shows the relation between the crank (with the marks) and the distributor (which can be set almost anywhere, even if the cam timing is off).

I know people talk about "jumping time," but personally I don't see how that could happen with destroying the timing set. But I can't prove it NEVER happened.

TipsyFox

Its possible the distributor hold down bolt came loose. (Timing light would be able to be used here) Unlikely that the gear from the cam to the distributor jumped, and more likely the chain jumped a sprocket meaning both the distributor and the cam would both be off in relation to the pistons. I know this is a different engine, but just had a friend with a Ford 351 with a similar sounding problem as yours, and it had indeed jumped the sprockets. When it was running (which was only possible when somebody was holding down the gas, otherwise it would die) it's timing was off like around 12 degrees.

Also is it possible that a vacuum leak developed? Maybe something is letting a bunch of unmetered air into the plenum causing the mixture to thin out, and the engine dying.

Aerodude180

Thanks Everyone

I'm going to check all of the hoses for a Vaccum leak.

If I pop the valve cover off is there any way to easily see if it has perhaps jumped a sprocket tooth? Rocker arm or distributer position at TDC ?


- Beyond that my question would be - what am I accomplishing by holding the Air flow Meter door partially open that is allowing it to run? I have the fuel pump jumped so its not that. Obviously its telling the ECU there is more air coming into the engine than there actually is - is the ECU then telling the injectors to spray more fuel, retard or advance timing or anything else?

Also, forgot to mention after it died, I tried many time to get it to start, I tried everything - it wasn't until I pulled the 7.5 charge fuse that it finally started and ran for about 2 minutes. I imagine I just have a bad / shorted alternator or voltage regulator. So for the time being I've been working on it with the 7.5 charge fuse out

skypilot

iTrader: (1)

Well, you really need 13.8vdc to run & charge the battery. If you hold the door open it allows the fuel pump to run. I think you more likely have the jumper wrong. Pull the valve cover and check your mechanical timing marks. If it spins fast on the starter its not building compression it did jump.

skypilot

iTrader: (1)

Now here's where I am missing something. If the engine runs the VAFM door is going to be open due to the engine running. Why do you need to hold it open? You must have air coming in through somewhere behind the TB.

jaysson_2012

I would check the basics first. Fuel filter could cause those symptoms too. And its cheap and easy to replace

Aerodude180

Worked on it all day today. Haven't tried fuel filter yet, but got through about half the vacuum lines.

In order to rule out that holding the Air door open is turning on the fuel pump - I've got 12vdc run directly to the pump, so its always on for testing purposes.

Situation remains the same - It will run for a few seconds then bogg down and die - but if I push the AFM door open with my finger and find the spot that's just right it will keep on running.

Also noticed that if it start it (without AFM door held open) and disconnect the TPS connector the idle will smooth out and it will keep running - can't drive it like this or move the throttle - but it will idle.

ECU error code is still oxygen sensor - which seems fine - possible because the air fuel mixture is off as I'm playing with it.

- I've also blocked the EGR valve inlet for the time being to rule that out.

scope103

If you've ruled out the VAF FC (fuel control circuit), a bad rheostat in the VAF could cause your symptoms. Have you tested the VAF? http://personal.utulsa.edu/~nathan-b...33volumeai.pdf

Aerodude180

I've metered both the TPS and VAF again and all are within spec at the sensors and at the ECU end of the wiring harness. The only thing that seems a little off is the TPS #2 test between the IDL and E2 terminals - the spec is for
less than 2300 ohms. I measure 26 ohms ...which is less but seems like a lot less....is this a bad TPS or is 26 ohms ok?

I tested the TPS according to spec's here:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

The engine is running so poorly I can't tell if it's idling down or not when I jump the T terminal.

Right now - just as an experiment I've got the air meter internally adjusted to the point where it will run - I suppose equivalent of me holding the door open. It will idle but not drivable. Looks good inside - bit of scoring on the PC board at fully closed but thats it.

scope103

26 ohms is fine (it's a switch, so zero ohms is perfect, but it's not a snap action switch so 2300 ohms is "meh."

I'm wondering if you have a "flat spot" in the VAF rheostat. You measure from VS to E2, and slooooowly open the vane. The resistance should change smoothly. If you get some spots that jump up or down, you might be sitting in a bad spot at "idle," and getting on a good spot with your finger on the vane.

dumptruck.thewookie

I love reading a post that exactly describes my symptoms...and then just stops posting....