SupraSport

Guys,
I got my 89 4runner back and running from a blown headgasket and now it has no power. Throttle response is almost zero.

I know 100% that the timing chain, cam gear, and distributor were installed correctly. I tuned the timing by idel first and idels OK but timing is at 20 BTDC!! I can adjust it as far as 15 BTDC with the adjustment room I have on the distributor, but idels poorly. When I jump the diagnostic box to do the timing(T and E1) there is no difference in the idel, the idel should drop. I also have one code coming up:

51-
IDL (tps) CONTACTS OFF, NEUTRAL START SWITCH OFF, A/C SWITCH "ON" SIGNAL TO ECU
--A/C SWITCH/CIRCUIT
--A/C AMPLIFIER
--TPS/CIRCUIT
--NEUTRAL START SWITCH/CIRCUIT
--ECU

I think my problem is the TPS. Anyone experience something similar? I'm going to go bench test the TPS now. Any advice would be great.

Thanks
Aaron

*NOTE- before I reset the ECU (Removed neg terminal) I was also getting code 42-
VEHICLE SPEED SENSOR SIGNAL CIRCUIT--NO SPD. SIGNAL FOR SEVERLA SECONDS WHILE VEHICLE IS OPERATED UNDER HEAVY LOAD (TPS/MAP/AIR FLOW INPUTS)
--SPEED SENSOR/CIRCUIT
--ECU

SupraSport

VTA-E2 reads 930 Ohms at closed Checks out OK
VTA-E2 reads 4.7 KOhms at WOT Checks out ok
Idl-E2 Is open at all throttle positions.... hmmm not OK?

Diagnosis:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

SupraSport

Vcc - E2 reads 6 kohms at any position Checks out OK

rdharper

Idl - E2 on my rig shows 10ohms in the throttle closed position, which is indeed < 2.3K as the chart shows. As the throttle is opened, there is a sharp change to open as the chart suggests.

Mine was misadjusted such that on the engine, the ECU only saw the open condition. That caused the engine to idle at 500rpm as the ECU "thought" the throttle was open and therefore the rpm's needed to be lowered Adjusting it correctly fixed the problem, allowing a smooth idle at 800rpm.

mr toytech

my truck did the same thing and the idle conntacts in the tps where corroded. i replaced it and the prob. was fixed.

SupraSport

I think I'll get a TPS from the dealer tommorow. Hopefully it will fix the problem.

Would a bad tps explain the timing being at 20-25 BTDC?

mr toytech

yes because its not getting a correct reading off the idle conntacts. witch helps to set your base timing. mine was also the 3.0 but the tps still works the same

rdharper

Yes. When I inherited the low idle, I also had a setting of 25 BTDC. These were the only two problems I've discovered on my one month old '94 4Runner.

Btw, I bought a used TPS on Ebay for $18 (shipped) which I used to understand how the thing worked. Also got the connector with 1" wire on it which makes a neat test connector. On the 3.0 it is a bit of a pain to get at the TPS. The TPS I got turned out to be good, as was the one on the truck. Just misadjusted. But I'll keep the one I bought for backup.

Good luck.

SupraSport

Guys, still need your help.

So I broke the bank and got the OEM TPS from toyota. First let me say that they have improved the design from the original and the new design looks much more durable.

I installed the TPS correctly thanks to 4crawler.com

The timing can now be set properly

I have no codes, CHECK ENGINE LIGHT IS OFF


Truck idels well but has no power still!!! Whats the next step????? What should I look into next. Any suggestions would be greatly appriciated!!

Thanks
Aaron

rdharper

My experience earlier on the TPS paralleled yours. Note mine was on my V6, the 22REC has never had the problem you've described, but the V6 has.

Now is a good time to pass the emissions test if needed. If not, I'd try bumping the timing to a scosh more advanced and see how much difference in power you get. Others may have a different idea, just passing on what I'd try. My V6 was dead at 8 degrees, but with good power at 12. Point is 4 degress can make a very big difference.

TNRabbit

You have to disconnect something to check the timing; I don't remember if it is the TPS or to wire across two terminals in the interface pinout...anyone know for sure? otherwise, you get the high BTDC reading because the ECU is adjusting it.

ovrrdrive

If you'll notice, he did that here:





To the OP:

Sounds like a really strange problem... Did you do a compression check?

Good plugs? Wires? All the basics covered?

You say it has no power, when it falls flat on its face does it do it smoothly or with a rough stutter?

Just trying to brainstorm a little...

SupraSport

Compression check is scheduled for tommorrow

It idels well, and stays smooth as I accellerate SLLLOOOOWWWLLLYYY. But if I hit the gas hard there is ALOT of valve chatter. I thought I might be bad gas since it has been sitting for a while but after fill up it's still having problems. It is also running hotter then usual. When coming to a stop it will bog down due to hitting the brakes (booster vacume pull).

I think I might inspect all of my vacume lines just to make sure I installed the rats nest properly

I had the valve seats redone and the intake/exhaust ported while I had the head off. I'm going to be pissed if the ˟˟˟˟ up the valve seats

Thanks for the help guys, we'll get this thing figured out.

SupraSport

Plugs, wires, cap, rotor are all good

TNRabbit

Lot of valve chatter; sure that isn't knocking/predetonation? That could account for the running hotter. How long was the gas sitting? Did you drain & refill? Try a bottle of StaBil in the tank and possibly Seafoam to clean everything out.

Vacuum lines sound like a good idea to check also....

TNRabbit

I re-read the post; was the timing 25 degrees BTDC with the pins bridged? I thought it was supposed to be 10-12 BTDC...? Did I misunderstand something?

SupraSport

Due to the bad TPS, when I bridged the connection the ECU did not think it was at idel and thus I could not set the timing. After replacing the TPS and adjusting it properly I was able to correctly set the timing.

But it still has poop for power, thus my problem.

UGATruck

I just got done fixing this same problem on my 94 pickup. The idle was ok, but I could get out and run faster than it could get up and go. It was ALL due to my TPS. If the TPS isn't set correctly, then it is impossible to set the timing correctly.

When I finally got my TPS adjusted, my timing was so far off I couldn't even see what it was reading. Re-adjusted the timing and the thing runs like never before. It's wonderful!

The key for me in adjusting the TPS was the trick on page 5 of theThrottle Body section of the Factory Service Manual If you look at (4)(b)-(d), you'll see how to correctly set the TPS. If you get (4)(b) right, then all the other tests are just for verification.

Hope this helps. Of course, I did not have valve chatter so that might be something else.

TNRabbit

SS: Did you figure it out yet? I'd guess the valve chatter you heard is the timing set so far in advance that you're getting pre-detonation. Did it go away when you got the timing set?

Also, another thing that can cause really poor power is the knock sensor (or wires to it); if it is bad or not reading, the ECU goes to maximum spark retard, which would accounf for the crappy power.

UGA: Thanks for the info & link! I've had this problem and your post helped a lot.

TNRabbit

What does the dealer charge for a TPS?