Need Help on drivabilty issue wont rev past 2800 or take an engine load

[tbcmorris]

ill try to be as detailed as i can.

the problem. car idles at 1000rpm, will not take any throttle over maybe a quater, will not rev past 2800 rpm (acts like its having its fuel cut, it will pop and backfire). will not take an engine load in gear, misfires, sort of hard strating starts perfect 2nd or 3rd time everytime.

the car ran fine before it was stolen. i got it back with broken afm wiring and missing bov and inter cooler piping.

motor work: weisco piston,eagle rods,crank work,ported and polieshed head,mm overszied valves, HKS camsshafts,60-1 ct 26

what i have tested and tried:
first brought everything back to stock. that included no boost conroller, no 550s,no lex afm.


afm was bad. bought a new one that that took care of the bad misfires.

rewired broken wires on isc. no change.

changed plugs, no change

compression checked while plugs were out 130 every cylinder.

vaccum tested. found small leak. fixed no change.

leak tested the intercooler piping no leaks.

check engine light code 11 changed under the intake manifold to where the coil packs ground no change.

code comes back intermittantly.


im lost at that guys. any help would be greatly appreciated. i really want to get this thing running right...im going on 10 monthes with this build and some seat time be fore winter would be AWESOME!!

 

[Supracentral]

I hate code 11 errors. It can indicate any number of wiring faults.

jetjock would probably more help with this (I PM'd him with a request he takes a look).

Honestly your symptoms sound like a TPS issue. Have you run it through the diagnostics?

 

[tbcmorris]

i sent jet jock the same link i pm'd you with. ill check the tps now.

 

[tbcmorris]

im not the greatest when it comes to check resitance on sensors and such. but i think i did it right and the tps is bad.


tsrm said this. between terminals e2 and vta at idle between .3 and 6.3 killa ohms i got . 03

at full open throttle between 3.5 and 10.3 i got .750 and open loop.

also....i just started the car with the tps not plugged in....same exact symtoms.

bad tps?

p.s. im not confident i did the other tests right...i may be ase certified...but im resitance checking retarded.:3d_frown:

 

[jetjock]

11 is caused by an interruption in the ECU +B/+B1 line. It can also be caused by a loss of ground but not as reliably as a loss of +B. A loss of +B will also kill the fuel pump so it's a double whammy for making the engine quit.

There are simple ways of dealing with this if you have the right gear and are electrically savvy but otherwise the best way is to first eliminate the ground side by verifying the integrity of Ground Point B from the intake manifold to the ECU. Alternately you can bring a new ground directly to the ECU and see if the code goes away. The problem could also be Ground Point C (left fender) because it supplies ground for the main relay.

Once the ground side is eliminated start looking at the +B side. That means the path through the fusible links, EFI fuse, and main relay to the ECU. One way to do that is to jumper around each one until the code clears or run +12 directly to +B/B1 on the ECU with a long (fused) jumper.

A quicker way is to connect a jumper from battery positive to the +B terminal in the diag block. If the code disappears you'll know the problem is in the +B side. Do this only as long as it takes to test and only after you've checked the obvious things like the main relay and fuse box. Pull and re-seat the relay for example. You can also try putting a meter on +B in the diag block and wiggling the harness in various places.

The idle problem could indeed be TPS related but it's moot in the face of an 11. Which reminds me, you will not be able to view other codes (assuming any are present) until the 11 is corrected.

 

[tbcmorris]

I won't be able to check anymore tonight I left my shop about an hour ago.

Hmmmm. Left side fender is off right now. Sounds like that might be it. Where do those ground wires ground to on the fender...its been so long since I took it off. The ground by the maf is good,intake manifold is ground is good,so are the grounds off the neg. Terminal.

If the fuel pump shut off that would cause the motor to stall if I'm correct. The car never stalled so I assume the interuption in power is not enought to kill the pump?

The mil comes on almost immediately after starting the car.

I will follow you diag steps tomarrow and reply with results. I think I understand everything in your post. So tomarrow should yeild some definate results.

 

[CajunKenny]

tbcmorris: Sorry for being off the subject here; but, I'm VERY curious...

How was your car stolen? Did they hot wire it, load it up on a dolly or something similar?

The reason I ask is because hopped car thefts are increasing in my area and I'm wondering about the effectiveness of the stock Anti-Theft system.

Thanks...

 

[jetjock]

When I say left fender I mean on the inside of the engine bay right behind the battery. As for the ground being "good" there's no way of knowing that unless it's either measured under load or substituted. We're talking about a very slight severance in the circuit here.

It's good the MIL comes on quickly. Clear the code, turn the key on, jumper battery positive to +B in the diag block, then start the engine and see what the MIL does. Be sure to turn the key on first before installing the jumper and remove the jumper before turning the key off. I doubt they'll be a problem if you don't but I'd rather the kind of jumper you can fit in there not carry load any longer than needed without help from the car's wiring.

 

[tbcmorris]

Cajun. Imo the toyota anti theft is a joke. The tumblers in my ignition were worn out. There was no damage to the ignition and it wasn't hotwire. My guess is it was started with a supra key.


Jet jock. The body ground coming off the negitive for the battery I'm assuning. Just painted my engine bay maybe I painted the threads. I will check that and check everything else you said today and post results. Thank you very much.

 

[tbcmorris]

ok i have made a little headway.

cleaned all the ground by the battery,cleaned terminals...code 11 gone.

when i twist the tps i get a change in engine rpm.
i did a contiueity check and all wires go where there susposed too.

i now get air flow meter, air intake temp and hac codes.

so i started checking the contiueity back to the ecu.
this is where i get confused.
blue red goes to blue red at the ecu
lt green goes to light green
lt green red goes to light green red
brown goes to brown


heres is where it gets wierd
the second brown wire gets contiuty to a pink wire(speed sensor in the gauge cluster) that and a knock sensor wire and goes to a yellow red gauge bezal wire. that yellow red also gets contiuity to the pink wire, brown and the knock sensor.


is this how its susposed to be?


thank you.

 

[jetjock]

That you can see other codes means 11 has been cleared. Let that be a lesson on grounding. I have the intake manifold grounds chained to the igniter and then to ground point C because I dislike having the ECU, igniter, and fuel injector grounds dependent on the block and chassis. I have yet to find one of these cars that didn't have excessive voltage drop in those circuits due to bad terminations. Same with the charging system wiring. The cars all ran OK but it was only been a matter of time before symptoms would've showed up. I avoid that by having everything grounded directly to the battery.

I assume you're talking about the AFM wires. Brown on the AFM is ground and so is one side of the speed sensor. Won't set the codes you have. Based on your symptom and what you said before about broken AFM wiring I'm not that surprised you have both AFM codes. You need to re-check that repair job and if it comes up OK you'll have to test the AFM itself. I smell wiring or connector problems though because you have both codes and because airflow and temp are separate and independent devices inside the AFM. The odds of both being bad are slim, especially considering air temp is nothing more than a thermistor.

Focus on getting rid of the airflow code first because it has the greatest effect on how the engine runs while the air temp and HAC have only minor impact. The HAC and air temp (signal THA) are simple enough, just follow the TSRM. You'll also need to check/set the TPS. Again, use the book for that.

 

[tbcmorris]

good call sir.

when i first rewired the afm i used the mitchell wiring diagram. the mitchell diagram was wrong. it the afm wired like this.

green
blue red
lt green red
lt green
brown
brown


wrong it wires



brown
blue red
lt green red'
lt green
brown

cahnged the wiring and she runs beutifully. thank you very much jet jock.

 

[jdub]

Amazing how well a logical diagnostic path works

Glad you got it fixed!

 

[jetjock]

Damn, a look at the 87 schematic shows the HAC would have been messed up by that too. Means I missed another clue to the problem. Must be getting old. You should be good to go although you might want to check the TPS since you moved it. Anyway, glad it turned out OK and good job. Our work here is done