bikedave99

Well, I'm new here, but I just bought an '88 Toyota XtraCab with 235,xxx miles. The previous owner bought it with a blown HG and transplanted a '94 engine and tranny into it. Here she is:


And heres the new ticker:


I drove it home and it ran like a champ, no issues, but I don't know its quirks yet. Drove ti about for the next few days then we got hammered here in AR with an ice storm that I'm sure others have been enjoying as well. What better time to find out what this thing can do right? Well, spent a day just kinda putt-sing around town going between 2 and 4wd as necessary.

I began to notice that if I tried to step on the accelerator quickly it would die out then revive when the engine slowed back down. I limped on home and opened the hood. It idled fine, but when you try and give it gas fast or slow past a certain rpm it just dies, then revives once it slows back down. I pulled off the air filter housing and checked that i didn't have any blockage which I didn't. I pulled the plug off what appears to be some sort of valve on the intake housing. It all looked clean so I plugged it all back up and buttoned it down, started it up, and it revved up just fine. So, I assumed it was that valve near the intake, or the plug connection going to it. I figured that something had gotten in there and stuck the valve, not allowing enough air in past a certain rpm. I went for another drive and it did it again, so I unplugged everything replugged it and it ran fine. The next time it did it i decided to stay in the car, stay rolling, and just kill the ignition while it gear for a few seconds then turn it back on. It fired right back up of course and revved fine. So, something is resetting when I turn off the ignition but I can't figure it out. This seems to be the knowledge base for this sort of thing so if anyone has any useful info I would appreciate it. I'm a newb to this forum but not to forums so I'd better say right now that I have searched and found nothing on this particular, but I really don't know what to search for a the problem is vague. Thanks guys!


Edit: Also, it does not always happen at the same rpm, it varies. Usually I can feel it starting to stall at a higher rpm then it will slowly works its way down to barely above an idle.

desconhecido

Is it throwing any sort of CEL code? Auto or manual transmission? Is the EFI from the 94 or original to the vehicle?

Could be a fuel issue, a spark issue, an electrical problem (such as 12v supply to the ECM or a grounding issue or an intermittent/partial short or a relay) or some combination of all these things. I think the place to start is checking to see if the fuel pump is shutting off when the problem happens -- does the fuel pump lose its 12vdc and if not does the fuel pressure drop?

Can you reproduce the problem in the driveway to see if you lose spark when it happens?

Or, check to see if the 12vdc to the ignition system is being interrupted. Is there a tac? If so, does it stop when the problem occurs?

Now, this is going to sound sort of crazy, but remove the fuses for everything that is not essential for making the truck go -- radio, lights, etc. -- and see if anything changes. Sometimes these trucks exhibit odd electrical problems (like a bad combo switch shutting off the speedometer). Also check the wiring to the under-hood fuse box. There are some big wires up there that seem to cause strange problems when crimps get weak.

There is an online FSM for early 90s 4Runners that has separate electrical diagrams for all the electrical systems on the vehicle. Probably the real place to start is to look over these diagrams for the fuel system and the spark/ignition system, figure out where the relays and test points are, and then get after it with a VOM.

Not an easy problem -- good luck.

bikedave99

Thanks a lot for your thoughtful response desconhecido. I will answer your questions as I can. As far as the codes, I looked all through the FSM to find the code interpretations and I couldn't find it so I have not yet checked to see if it is throwing any.

The problem with this problem is that it is sporatic. This I could handle, however, as the problem causes it to quit, which makes it all reset and then work fine, it gets a little frustrating.

Now, to maybe unearth a few more clues. Maybe I need to be a little more clear on the stalling out thing. It does not want to quit on its own. For example, if I were to floor the pedal, it would rev up to the wherever it was kicking off and sputter out. Now, with the pedal still floored, the engine will slow down and then come back to life for a second as it fires and tries to rev up again and quits.

Also, my gauge lights no longer come on, nor do lights behind my heater controls. I need to check the fuses on that...

Let me finish answering the questions. It is a manual and the EFI came with the motor so is '94.

desconhecido

The online FSM for the 93 should apply to the EFI from the 94 also. See http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf for information on CEL error codes. If the ECM detects an error, the CEL light should be on. Hopefully the CEL is properly connected and glows when you turn the switch to "on" with the motor not running.

The way you describe it it seems like it might be a fuel delivery question which would make me look at the fuel pump, fuel pressure regulator, and fuel filter. Also, the circuit opening relay which is controlled by the AFM. Or the EFI main relay. If it's an ignition question, for example, if the distributor, for some reason, were to stop sending cam position information, I would think you'd get a CEL and error code.

edit:
Of course, there are all the usual suspects that you can look at like vacuum leaks, malfunctioning EGR, dirty throttle body, throttle position sensor, plugs, rotors, wires, coil and igniter, etc. But, it seems to me that none of these items should give you seemingly random shutdowns. Might want to check out the throttle position sensor for smooth operation, though. Also, because you are experiencing wiring/electrical issues and there are electronic components and wiring imported from the 94, it would probably be a good idea to check wiring connectors and grounds.