92 Yoda

My 1988-89 4Runner has been giving me heck over the past 2 months and I'm just about at wits' end with it. I had a no start issue about a month ago due to some poor wiring a previous owner had done which took me ages to figure out which. Now seemingly out of no where I have a serious bogging/hesitation and misfire issue. Let me explain the symptoms.

The truck starts up fine, runs the warm up cycle fine and when the RPM's drop after warm up it idles fine... as long as I don't touch it or rev it. If I go to give it some gas it immediately bogs down and almost dies. If I feather the throttle I can get it above 2500k and it runs fine, however when I let off it doesn't return to a regular idle; it begins misfiring with the RPM dropping to near stall. After 10-15 seconds of misfiring it will return to a nice idle as RPMs increase again. All of this is done from the engine bay and because I haven't tried driving it since it all started.

As far as trouble shooting goes I've pulled the AFM and tested it finding erratic resistance throughout the flapper range and changed it. I've tested the TPS which checked out all in spec with a little adjustment, and I've also changed the Cap and Rotor on the dizzy. Before this recent issue started, when I had the no start, the coil tested in spec and the fuel pump was checked as well with no issues. I've also re-gapped all the plugs to spec and done a compression test with pressure ranging from 160-170 PSI in all cylinders.

After changing the AFM I noticed slightly less hesitation however I still feel like it would be undriveable in it's current state. Today I'm going to change the TPS anyway in case I missed something when testing it. One major pain in the ass is that the cluster is not factory and was swapped from an automatic V6 of the same year. I'm not sure if the wiring isn't compatible or the bulb is out but the check engine light isn't working so I can't just check for codes which would save me some trouble. I've been thinking about pulling it and checking the bulb or trying to wire an external check engine light but for now I'm holding out.

If the TPS doesn't solve the issue I'm thinking maybe O2 sensor or distributor but right now I just don't want to throw any more money or time at it as I've got another truck needing body work that I plan to drive this summer.

Finally if you're just going to tell me to search the forums I've been doing that for the past week and have checked pretty much everything suggested (AFM, TPS, Fuel Filter, Compression, Fuel Pump, etc). If you have advice about a similar issue you've had or know how to wire a light to externally check for codes I'd love to hear it.

Thanks for any help!

wyoming9

iTrader: (1)

Has the fuel filter been changed ??

Remember stepping on the throttle just gives the engine more air not fuel

92 Yoda

Filters been changed, I'm somewhat convinced it's not fuel because it starts and runs fine at high rpm... It's just the transition from idle to high rpm and back that seems to be the issue.

92 Yoda

Anyone else?

bootscootboogie

iTrader: (1)

I do not own a 22RE but I can't tell you how many threads like this one I've seen end up being an issue with the wiring harness. Something to do with it being very weak and when it gets hot it stops sending the appropriate voltage? Something to check out. Good luck dude.

an1176

Have you checked timing chain guides? It could've jumped time if the guide is broke. O2 sensor, fuel related, huge vacuum leak, and cat are about all I can think of.

an1176

Also before you start throwing parts it the first one I would do is get your cel light going and check codes.

punks_is_4x4

The tps did this exact same thing for me I could only drive it while the engine heated up. I was battling with the sensor on top of the thermostat housing the afm and the tps. To my knowledge the tps is a huge problem it has to be set perfectly I don't know if you have taken yr throttle body off when adjusting but I would definitely take it off to do the adjustment and if u don't have the exact measurement of feeler gauge get one because like I said it has to be perfect. Are u getting any smoke when it bogs out the tail pipe? Color? I was getting black smoke like to much fuel and the o2 sensor picked that up and tells the ecu so it kills the engine. I leaned out the air fuel ration on the internals of the afm. The water sensor I was battling with didn't have to do anything with it I don't believe. If u can't get it exact find a Toyota shop or maybe even the dealer and ask to speak with the head technician ask them if they can set the tps for U on the throttle body. Might be spendy but you will have that part taken care of and can check that off yr list. If you swapped out the afm it's probably fine. U can pull the bulb off the cluster for ur cel and hook it to a 9 volt batter I believe and check it that way to seeing the bulb works

Superstud

Clogged jet?

92 Yoda

I've been trying to convince myself I wouldn't have to get into the harness again but with everything I check it's getting closer to it. Might try cleaning all the ground straps first.

Haven't yet but I've been meaning to double check timing just need to borrow a light.

Removed the throttle body and got the TPS exactly in spec with a feeler gauge. I plan on pulling the whole intake manifold to clean and check all the sensors. While it's off I'm going to replace all the vac lines and gaskets to hopefully rule out any air leaks. I tried to fix the CEL today but couldn't figure out the circuit, next is to find an original cluster for cheap.

hahaha I wish

crawler85

Do you know the ACTUAL fuel pressure?

Sounds like my problem, my fuel pump was only putting out 20 psi when it shouldve been around 33-38 psi.

Terrys87

iTrader: (1)

I have had old TPS pass test but when I installed a new one it made a huge difference. The TPS has been cycled millions of time on a high mileage truck. I normally squeeze every mile out of some parts. The TPS is one I will change if I suspect it at fault.

Your cluster will work even if it is from a 3.0 motor, I have one in one of my trucks. Just adjusted the tachometer and works great. Not sure what else could be causing some of your problems.

May be a dumb question but is the cluster a match as far as auto to auto or manual to manual. They do vary some. Not sure if the CEL matters or not as far as clusters and if they are wired the same.

92 Yoda

I'm going to grab a gauge and check that as well today.

Well I got a good used TPS but just found out it doesn't fit because it's got a different connector.... too bad I already installed and adjusted it haha Ill have to track one down to be sure.

And the cluster is from a Auto v6 Sr5 and my trucks a manual 22re. I feel like they must be wired differently somehow because I can't even get the CEL to turn on with accessories. I've tried switching out bulbs but nothings working.

BajaRunner

I'd definitely go and replace the bulb for CEL. That would make things a lot easier IMO!

It does sound like a TPS issue. My last 22RE I had tested it 100 times and always checked out fine. I put a new one on and it fixed my problem (Poor acceleration and lack of power).

jham819

adjust tps accordingly along with your distributor timing, i spent 100's on parts and hours tracing wiring and it turned out it just was all out of adjustment.

92 Yoda

I finally got some time to work on it tomorrow but how would this all get out of adjustment all of a sudden. This thing ran like a clock the weak before then just up and decided to quit.

punks_is_4x4

Sometimes it's not as solid as u think or wasn't set 100% did u take the throttle body off? To adjust the tps

92 Yoda

Thanks for all the help guys! Ended up getting her going again. Turns out I had a broken wire at the fuel pump connection and a loose terminal on the pump. It runs better than ever now with the freshly adjusted TPS and new AFM. I'm taking it cross country next week so fingers crossed this'll be the last of my issues!

punks_is_4x4

Awesome glad to hear you got it tracked down having a gremlin ruin truck can be extremely frustrating