chukarhunt

Hey everybody,

I am on the last stretch of my 1uzfe conversion (1992 Toyota pickup 5 speed manual) but have run in to some ‘serious’ issues. The engine is in the truck, but when it comes to running, there are a few obvious issues, of which I need help narrowing down. Check engine light is on obviously, and I can run codes.

First, let me start with codes. I was getting 27, 29, and 31. 27 and 29 is the right o2 sensor. I replaced the sensor with a new one, and I still got the codes. 31 is a vacuum sensor signal on the afm, no idea what that is all about.

When I plug in the iac valve, truck goes to super low idle. First hit of the throttle and it is super responsive, but another rev and it quickly starts to run like complete crap, super low idle, severe over fueling (the eyes and throat burn) and misfires like crazy and stumbles like no other. Unplug the iac and it idles smoothly and seems to run fine, no overfueling, can rev the crap out of the engine, but throttle is less responsive, but still acceptable.

with the iac unplugged, I can take it for a drive, but I can’t go fast. You have to be gentle on the throttle and ease on the acceleration, otherwise it cuts out and stumbles under load. Truck in neutral, can rev like crazy but if you plant your foot in it it stumbles as well. As the truck warms up, it runs better and gains power, but still wants to stumble. Under fueling?

Now, here is the bad part.... I finally wired up the alternator and plugged it in. Tried to start the truck, and it did not want to start. When it finally fired, it would backfire and chug and spit and not idle one bit, have to pump the throttle to try to keep it alive. Whole time trying to do this, the check engine light flashes on and off with the rhythm of the spitting and chugging. Won’t run for crap. Unplug the alternator, idles fine, back to stumbling under load. What the crap....

And now, I can’t run codes! When I ground out te1, the check engine light stays solid. Some threads I have read say I have a bad ecu. Did the alternator just fry my ecu? The truck fires up and idles fine, it just can’t get anywhere under load. My fuel pump relay is an add on, so I know it is sending full 12 volts to the pump. I am at a loss at what to do. Any insight would make my year. Been 10 months at this and just want it done. I know custom wiring is tricky to solve over the internet, but I swear my alternator ain’t hooked to the ecu, and why does the iac make the truck run like crap?

thanks again!

Moarpower

Are you using a stand alone Ecu? If not, you should.
It sounds like you afm or afm signal is bad. Also, what alternater did you use? Under or over voltage issue maybe

chukarhunt

Hi Moarpower,

I am using the donor vehicles ecu, 34 28 16 22 pin ecu. Before all this happened, I got the afm code once, but after careful study rewired it and the code went away. You still think the afm could be the issue? It must use signals from the iac?

it is the stock alternator on the 1uz. So you are saying the ecu may be seeing more than say “16” volts and it is trying to protect itself?

Moarpower

I would seriously look into getting a stand alone Ecu for your truck. Will solve a lot of headaches.

​​​​​​The issue here is that the Ecu could also bad, as they are notorious for failing with age and use. Have you opened up the Ecu to see if any of the capacitors are leaking?

As for the running, I dont think think it's underfueling, it's just not getting the correct signals. This is usually the afm, or Ecu. Do not clean the afm, whatever you do. It will kill it. But take out the iac, make sure it can rotate, clean with carb cleaner.

Afm and Ecu are my first 2 thoughts without knowing g what troubleshooting you've already done. In this case both could be bad. See if you can check the ecu

chukarhunt

Thanks for the input. I have opened up the ecu, and didn’t see anything out of the ordinary. Each capacitor looked like the next one, but I will open it up again since the alternator incident.

chukarhunt

And I don’t mind the stand alone ecu, I just can’t swallow the price. What would you recommend?

Moarpower

They aren't cheap. But they are all pretty much the same. Your best bet is to just watch Facebook groups and other online sake groups to get a used one. How did you trick the Ecu into thinking the auto trans was still installed?

chukarhunt

I followed instructions from a gentleman by the name of Nigel Wade, if that rings a bell here. He said this particular ecu does not need any tricking, it just runs.

the megasquirt 1 is a decent price, but obviously has its limitations. Would it still be a good choice for this engine to get started anyway, later upgrading to ms3 as money became available?

jadu

iTrader: (42)

sounds like when you take the alternator out of circuit, it idles fine-as you may already know, when you do this you're running off the battery and sounds like the battery is healthy providing enough current and voltage for the car to idle. If you havent done so already, I'd first grab a DMM and check the DC voltage to see if the alternator is providing enough voltage to charge the battery.

chukarhunt

I appreciate the input. I tried to measure the voltage coming from the alternator, but I can’t get the engine to stay running with the alternator plugged in, so I am at a loss.

jadu

iTrader: (42)

I see. Although not recommended, you can disconnect the battery when the car is running and it should run off the alternator. I know it's taking a step back, but I'd get the alternator tested at autozone or something. You may continue troubleshooting like you're doing with the alternator out of circuit, but have a battery charger handy to charge your battery.

Also, a bad MAF also caused my car to sputter, and spew black soot out the exhaust-dont know if you have changed that out already.

good luck

dicer

You could be dealing with a bad Idle air control motor the bearings can go bad and mess it up. You could be like one poster says be dealing with a bad ecu. Is your set up using the stock transmission? A stand alone ecu will not break the bank if you go with a mega squirt but then if you have an electronic transmission then you will need a controller for that.
There might be some help on this site.
http://www.lextreme.com/forums/index.php

chukarhunt

Thanks dicer. So a little more background. I bought and installed a used afm and idle control valve from a junkyard and swapped them out. as far as the afm I do not know that it changed anything. But, it may be worth swapping the old iac back in and see what happens.

the iac I bought from the junkyard does work. I can manually open and close the valve by grounding out the pins in order. I could not do that with the original iac.

i am running a manual, the r150f. Gonna unplug the afm tonight and see if that changes how it runs.

i like the idea better and better of running megasquirt, but I need to save up for it, even the diy boards. Would love to tune this engine. Always wanted a turbo down the road too haha. One step at a time I suppose.

Moarpower

I'd suggest looking around on the toymods forums.

chukarhunt

So last night I unplugged the afm and ran it, no noticeable difference. Then, I took a clamp and pinched the return fuel line closed. Engine went to a lower idle, but ran better. I had better power under acceleration, but was still stumbling in the higher rpms. Any thoughts?