88 4runner running rough
 

I know that this topic has been beaten up but I feel that my situation may be a bit unique.

Here's the deal, it's an 1988 4runner with the 22re motor. The motor is more or less brand new and has been rebuilt by myself. The motor has a 268 cam, engnbldr RV head, LCE headers and has been bored .03 over. None of this should take into affect on how the motor actually idles or runs with the exception of the cam. The motor also has new spark plugs, cables, cap, rotor, fuel filter, throttle position sensor, afm, o2 sensor, knock sensor, air filter, coolant temp sensor, and every sensor on the motor that can be tested via the FSM has been tested and checks out okay.

A little history that may be important: The original motor in this 4runner was a 22re motor. The p/o did a rte swap, after it spun a rod bearing I rebuilt a 22re motor and put the drive train back to stock (the reason for all the new sensors).

I have about 3300 miles on this motor and it has run great except for horrible gas mileage. I chaulked that up to the fact that I was still using the 22rte ecu. I was still using the 22rte ecu because I didn't have a new knock sensor for the 22re ecu. When using the 22rte ecu the motor ran good except it felt like I was getting fuel cut at 4000 RPM's. Now I have the 22re knock sensor and plugged in the 22re ecu (yes, it's the proper year and transmission ecu), and it runs like garbage!

I'm not getting any CEL with either ECU plugged in. I would just keep running the RTE ecu but I don't like that my motor bogs down at 4k rpm.

The throttle body has been adjusted per the FSM, the timing is dead nuts on at 5* with the diag port jumpered, good oil pressure, engine comes up to temp fine. Adjusting the idle doesn't seem to have any real affect on how it runs.

Here is where the experts chime in... I have built the motor by the FSM and tested EVERY sensor as per the FSM. To my knowledge, the elec and efi circuits/wiring are perfectly good and operating within range.

Forgot to mention:
I have new ground wires throughout the motor, the EGR has been deleted along with ALL vacuum lines with the exception of the fuel pressure regulator, charcoal canister and the brake booster. All other vacuum ports have been capped off and I do not have any known vacuum leaks.

I guess I should explain more than "it runs like garbage"!
When using the RE ecu, the motor idles VERY rough at about 500-700 RPM, the idle adjustment screw on the throttle body has no affect at all. When I give it gas it will stumble and hesitate to raise RPM's and when it does it will bog down at anywhere between 2500-3000 RPM. When it does bog down I hear like a weird hollow sound coming from the AFM. I'm assuming that is because the door in the AFM is suddenly closing and I'm hearing a vacuum coming from the AFM... maybe?

So, I got to thinking... I doubt it's anything sensor, mechanical or vacuum related. I get two different problems with two different ecu's. The RTE ecu just bogs down at 4k RPM, the RE ecu idles very rough and bogs down between 2500-3000 rpm. Both ecu's run pretty much the same with the exception of fuel mapping and the RTE ecu has provisions for fuel cut in conditions of over boost.

I know for a fact that the engine and everything connected to it including the engine wiring harness is good. I believe that both of my ecu's are good as well. So, I thought that maybe there is something wrong with the body wiring harness that controls either the coil, o2 sensor or AFM. But It's not the coil, the coil gets power and sends it to the distributor like it should. The o2 sensor wouldn't cause this, if there was an issue with the o2 sensor the ECU would just run in open loop mode and cause the motor to run rich.

So, I started looking into the pin-out differences between the RE ecu and the RTE ecu on the body wiring harness side thinking that maybe the p/o changed something to make the RTE motor work correctly. I looked into the plug on the body wiring harness that goes into the ECU. I noticed that I do not have a pin in that plug for the VC. The VC goes from the ECU to the AFM. I'm not sure what that specific wire control on the AFM but it would kind of make sense. If the AFM is not giving either ECU the correct signal I would get some issues like I'm having. I stated before that the differences between the two ecu's is the fuel mapping. Well, it would make sense that I'm getting bogging at different rpm's with each ECU if it could be something related to the AFM. But the question is, why would the p/o delete the VC wire?

Since there has been almost 70 views on this thread and no replies I thought that I would think out loud here and see what others may have to say about my train of thought. Feel free to speak up regardless whether you think right or not. I'm open to ideas.

I'll chase the VC wire tomorrow and update this thread. Once again, feel free to chime in with your thoughts!

oh jeez. ok. ummmm. well, afm was what first came to mind. im gunna GUESS (i hate that word but its the best i've got here) the afms are different between the motors. are you running the correct one? my guess is only based on the fact that the turbo motor pushes much more air.

You are right about the two motors using different AFM's. I am using the 22re AFM out of a 88 truck. The AFM has been tested per the FSM and is within all ranges.

A couple updates:

1) I was wrong about the VC wire, I was looking at my plug wrong. The wire that I do not have is the E21 wire. To test and make sure I was looking at the plugs right I did a continuity test on the VC pin on the ECU and the AFM plug and it checked out okay. From what I have found is that the E21 and E2 are grounded together. Maybe in 88 toyota didn't use a E21 sensor ground on the body wiring harness?

2) I double checked all the sensors or anything in the FSM EFI section that could be tested. My fuel injectors are at 4.1-4.3 ohms of resistance. The FSM says I should be between 1-2.5 ohms.

So knowing that my injectors are off by that much I would definitely think that they should be replaced. But, seeing as that I have over 3k miles on these injectors like this, wouldn't that have burned up my ecu or injectors completely by now and causing my engine to not run at all?

For a bunch of Toyota guru's I expected a lot more conversation than this... :roll: