Ole Red 1987

I've been getting codes for the past few months, its mostly been 11 (tps, ecu) I have replaced the TPS because it was having problems idling. i bought a new tps and when i hooked up the new tps it idled great but under a load it struggles, the engine will jerk, and it will through codes.

I'm thinking i have a bad tps wire (a short somewhere) because the codes dont stay on even if it just threw the code.

if it helps i bought this runner non running had a broken timing chain. I had the head machined and went through what was warn out. When i got it running it would throw code 11 under a load but this went away for about a month.

ive ran out of ideas and am getting frustrated

Cadin

I had an '87 (Pickup motor in an '85 Runner) did the same thing, took ~2 1/2 years (Distant Weekend Project Rig) of mind bending frustration, ended up being the fuel pump. I have also seen similar problems with rotten or damaged fuel hard lines from the tank bracket.

Do they salt the roads where you live? How long did the tank set for? Is it corroded? Clean fuel filter?

Threw all kinds of TPS codes (Code 11 among them). I guess it just wasn't getting enough pressure.

Otherwise, just shoot the system e.g. MAF,TPS,etc... with a multimeter per the FSM. I have second guessed the system many times, and it has been fine; often the issue was air/fuel related. Toyota's setup is pretty simple and rugged.

A great idle with loss of power under load sounds like a fuel issue to me.

Ole Red 1987

I live in the salt lake valley so yea they ice the roads got 8in of snow yesterday.


Is there a way to check the fuel pump electrically. I know of the bypass the FP jump. I've tested the pressure on that (without the truck running cuz it wouldn't start) I got 40psi. Isn't it supposed to be between 38-40 psi?

Thanks for the information.

Cadin

Was that at the fuel rail? How long did it keep pressure?

I'm not sure about the spec psi, but if you have suffiecient pressure the electrical part of the pump should be fine.

Can you get it to idle and fall with the Fuel Press. Gauge on it? Could your injectors be clogged?

At the time I had a known good unit on hand (and no FP Gauge) and just r&r'd to troubleshoot.

The FSM should have the ohm value for the pump, you should be able to find a free .pdf with the FSM. Have you gotten time to shoot the values for the TPS and MAF?

Enjoy the hunt!

Ole Red 1987

when i checked the pressure it was at the cold start injector. i am going to test it again this weekend this time where it goes into the rail.

i got the tps within specs when i installed it which waas about two weeks ago.

i was driving home from school today and besides throwing codes (this time it was 10 the starter not being hooked up to the ecu during diagnostic) and it would have a hard time idling, it sounded like it wanted to die. but it would go away with my foot on the gas.

the truck sat for about 2 months not running as far as i know, but it did have a full tank.

Cadin

How's the MAF?

Now it is stumbling on idle and going away with enough fuel? Sounds like she needs cleaned out. Old fuel may have a bit of water in it, have you tried anything to "dry" your gas?

Fuel additives with poly-ethyl amines (PEA's) are a good bet for crud in the system; just look for anything with amines listed, most other stuff is repackaged kerosene or JP-8.

diadromous

Had a similar problem with my 85 pickup, after going through the electrical side thoroughly and growing increasingly frustrated I changed my fuel filter and she ran like new. I forgot the old adage KISS; keep it simple stupid. The solution to most problems is the simplest.

Ole Red 1987

I have run a few tanks of fuel through it and when I was working on it a replaced the fuel filter. I will check that today. When it got cold here about 10 degrees it wouldn't start till I got it in the garage and warmed up, and before this it would have a hard time starting in the morning I think there's a bad check valve or corroded fuel line.

I haven't check the MAF, I will also check that today

Cadin

A bad check valve or fuel line should show up if you observe the pressure drop quickly after the pump is turned off while checking pressure. Interesting that it wouldn't start with it being 10F.

FWIW: I also had an '87 Turbo that would run like junk, and then be fine intermittently, and it was that the ground from the head was loose.

Also the crimps/butt splices inside the loom where the injectors (+) join are a classic place for corrosion. (Though I think this is more common on 22rte's).

If you have a local pick n pull you could grab a set of injectors for cheap, and swap them , I do this just to have my rig running while I send a set off for rebuild (Witchhunter).

All this being said, I have to concur with the KISS mentality, because most every time my truck has had gremlins, it has been some goofy detail I missed.

You'll find it!

Ole Red 1987

I did find a leak today where it goes into the fuel rail. I couldn't see it at first but once it warmed up it started spraying fuel.
I did hook up a psi gauge and it was reading 30 when I would rev up the engine it would go down. It would drop to 10 and probably lower but once I let up on the throttle it would take a second to return to normal idling
I pulled the codes and got 10&11 and it only flashes codes while driving when It changes gears

Cadin

Fuel pressure per the FSM is 38-44, jumpered and off;
38-44 vac disconnected from Fuel Press Reg @ idle (no jumper)
33-37 vac connected to Fuel Press Reg @ idle. (no jumper)

Should keep 21 psi @ five minutes after shut down. (no jumper)

-Get bunch of copper crush washers, rather than torquing down the ones you have. I think the size is the same for the filter and rail intake, so you will use them in the future.



You're almost there! -Fuel pump, (check valve), injectors, or fuel pressure reg. are the suspicious characters at this point.

Do injectors get clogged open?


P.S. Have you peeked at the hard-lines on the pump bracket? The access door is under the rear passenger side seat.

Ole Red 1987

It has to be fuel related as you said. I wrapped some duct tape around the intake boot because it had some cracks in it. It ran better but the engine still jumps around at higher RPM(3500-400) until I let of the throttle. I also replaced the bad fuel line.

When it shakes it seems like there's not enough fuel. It shakes pretty hard too.

I'm getting closer, thanks for the help

Cadin

Did you find the answer to your woes? (Make sure you post it so we can all know what the problem turned out to be!)

Ole Red 1987

I havn't fixed the problem yet but I'm pretty sure on what it is. For code 11 I'm going to reset the tps and see if that works. It will only go off at 3,500 rpm and will flash repetivly if held there.
code 10 which is the starter not being hooked up to computer on diagnostic check. I traced the starter wire up through the firewall on the drivers side. From there it goes up to the base of the steering wheel and goes into a connection that has to go to the computer, because when I was moving he wires around the truck ran for a minute but as soon as I hit the curb it died.
I tried many things to get it started but it wouldn't. It would only crank, bypassing the fuel pump didn't work and it wouldn't read any codes on the dash, it wouldn't flash at all when bypassed. So I went with the old wire shake test shaking the wires and cranking the truck. A few seconds later it started.
Now I need to look in there and find the short.

I forgot about the shaking and the fuel. Well I found a bad fuel line that would only start leaking when the rubber hose warmed up.

Ole Red 1987

Well I figure out the problems. I fixed code 11 by resetting the tps. For code 10 the PO rerouted the starter going strait from the ignition to the starter
Well it's supposed to go through the computer before it goes to the starter. The good thing is its easy to route it back to the computer, the problem is I have no clue why he routed the wire this way. Hopefully it's a bad relay and not frayed wiring or the worse or not knowing.

Cadin

Awesome!

The hardest part sometimes is finding what the PO was messing with!

Ole Red 1987

Well it still throwing code 11. I have absolutely no clue why. I've reset the TPS countless times using 4crawlers website, timing, new intake boot, tested the readings at the computer read the same as at the TPS. I know my neutral safety switch doesn't work but i bypassed so the computer thinks its in park.

In the intake manifold it has a lot of carbon buildup. I cleaned the throttle body without the Tps on, but its still in the intake

The part that confuses me is that when i jumper TE and E1 it will give me code 1 until I put my foot on the throttle. Then it gives me code 11 until I bring my foot off and let it finish counting to 11. It'll do this whether the truck is running or not.

When its running the engine will jerk when revved and when it does it when i'm driving it will jerk right before it shifts and the light goes off at the same time.

Well i went to a shop near where I live and the guy said it could be because of the AFM, crankshaft sensor which must be the knock sensor, or a bad ground or connection. He also said that sometimes the computer would give codes for other things that were wrong. i cleaned the AFM because it looks like a lot of dirt got in there at one point. After i cleaned it it idled better but didn't fix the problem.

Could the computer be getting codes confused? I'm going to check and clean all the grounds and connections but it doesn't explain why it starts to read codes (when jumpered) with the throttle open and the truck not running. This makes me think its electrical.

Any Ideas?

Cadin

Well, you can test the MAF/AFM with a multimeter pretty easily. You said it always kicks off at 3500 rpm. Maybe make a note of how your throttle is positioned/angled at this rpm, and turn it through that range (engine off) and see if the tps has an open signal around there (infinite ohms).

Did you ever get your fuel pressure to meet the spec above? Does it keep pressure when you turn it off? For how long?

I doubt the knock sensor is the problem, as it would just alter the timing for a knock. Sometimes the oxygen sensor gets confused, but it will usually throw the o2 code.

The three that really work in concert are the AFM-TPS-oxygen sensor to monitor air-fuel-and complete combustion.

What wires did you wiggle to work? Have you tested your injector wires with a multi-meter whilst wiggling?

Ole Red 1987

I finally figured it out. The either the ground wire (E2) or the VTA wire which works when the engine is above 1500 rpm. I spliced in new wires going around the factory harness.
When I did this it stopped throwing codes for the tps but started throwing them for the AFM and water temp sensor. I hooked up the E2 wire to them and no codes
Now the throttle is much smoother and the engine won't stumble under a load.

The wires that I wiggled were the ones that go straight from the passenger fender then under the throttle body. It threw a code when they were wiggled. It was not jumpered at the time.

That was a pain but I'm glad it's fixed.

Cadin

Glad you found it!

The splices for the injectors are right in there too, and are often very corroded! That whole section of the harness often has issues.