Car troubles...woe is me.

[Turbo. Targa. Life.]

Basics: 1990 turbo, a/t
Mods: SSQV, wastegate shimmed to around 8psi
Symptoms: car hesitates and what not off idle. Will not idle on it's own. Once past around 2500rpm's car revs very freely. Running rich. No vacuum.
Things I've tried: Coil Pack, Plug wires, plugs, cam timing, ignition timing, vac hoses, IC piping. Just finished an OEM head gasket job with ARP's and moly to 82lb ft. Also replaced intake manifold gasket with brand new felpro
CODES: 51 and 52

Anyone have any ideas? I know it says the TPS is the faultor, but I checked it according to the TSRM and found everything to be within acceptable limits.

Thanks for reading guys!
Brandon

 

[jetjock]

Brandon, just because the TPS checks out (no offense but I have no idea if it was tested properly) doesn't mean the wiring can't be at fault. Unplug the TPS and short IDL and E2 together on the harness connector to see if 51 goes away. No need to start the engine. If 51 remains the problem is in the wiring. If it does go away start the engine and check the idle for improvement. Don't expect the engine to rev past a couple thousand rpm set up like that though. 52 is of course a knock sensor/wiring issue.

 

[Turbo. Targa. Life.]

Here's my biggest beef with code 52, I just did a complete knock sensor rewire and it took 52 away. Now that it's idling the way it is, it's throwing a 52 again. HOPEFULLY 52 will disappear when 51 does.

Anyway, I'm gonna try shorting out IDL and E2 and see if that helps, I had totally forgotten about trying that. I'll get back to you JJ, thanks a ton

PS: it was tested correctly, I'm electrically advanced a multimeter is part of my daily job (car stereo install) and a feeler gauge is...well is self explanatory; but thanks for your concern haha

 

[jetjock]

Can't help on 52 other than to say the two codes shouldn't be connected unless it's a major wiring issue in the main harness somewhere. Short those two pins and see what happens on the 51 though. If it goes away check idle quality. After checking idle try holding 4K. That way you'll recognize RPM cut if it ever happens.

 

[Turbo. Targa. Life.]

LOL well RPM cut is kinda cool I guess

51 went away, but now I have a 41. 52 remains. Idle quality is still poopy...well actually it's nonexistant; it will idle for about 3 seconds on it's own, very bouncily, then die. Am I on the right track here?

 

[suprahooked]

No vacuum? How is your intake gasket?

 

[Turbo. Targa. Life.]

Forgot that part, just replaced the intake manifold gasket as well with a brand new felpro

 

[jetjock]

41 is expected because VTA was open. Your gasket may well be the idle issue but all I care about is getting rid of codes as that should always be the first step. If 51 went away either the IDL contact is bad, the TPS needs adjustment, or the connector is bad. You didn't say if you measured it on or off the TB but something is wrong there.

Fair nuff about the meter. Just that experience has shown some people can't use one even with detailed instructions. Let's face it, there are folks out there who could screw up a rock fight. That and when people post "I checked something and it's good" it's basically meaningless. Like when they say the wiring "looks good". Always cracks me up. They probably dislike paying for electricity each month because they've never seen it...

 

[Turbo. Targa. Life.]

I'm with you on getting rid of the codes, that's my first woe. SO, could you explain the adjustment procedure for the TPS to me?
Oh and I tested the TPS with it still on the TB. Is that bad?

just went and grabbed the readings i wrote down and dumbass me forgot to write down the .4-.5mm and the .75-.9mm readings...

closed: VTA/E2 .67k ohms (acceptable=.2-1.2kO)
WOT: VTA/E2 4.72kohms (acceptable=3.5-10.3kO)
WOT: VC/E2 6.38kohms (acceptable= 4.25-8.25kO)

 

[jetjock]

Where's IDL and E2? That's the one you need to be concerned with. It's what causes code 51. No, adjusting the TPS on the car isn't bad, just more of a hassle. It's easier to do with the TB off the car.

Since you just proved the wiring is good the resistance you measured across IDL and E2 must not be low enough with the throttle closed. It should be below what the book says. What's that, about 2K ohms? Myself, I wouldn't use a TPS that measured out that high. Most are much lower, around 10-50 ohms.

Set it up according to the book. My method is as follows: 1) Check throttle linkage for binding or disconnect it. 2) Set throttle plate fully closed using throttle stop screw. 3) Set TPS using feeler gauges as per spec. 4) Set dashpot using dashpot screw. 5) Reconnect linkage being sure it doesn't end up opening the throttle even the slightest amount. Adjust linkage if needed. (It's very rare that'll need to be done).

You don't need to get all crazy with the feeler gauge stuff. You could just set IDL and E2 to show low resistance when the throttle is closed and high when the throttle is cracked. Or use code 51 to do the same. The feeler gauge stuff is for emissions purposes and for the ECU to use as a backup if the VTA part of the TPS fails. IDL still needs to connect to E2 every time the throttle is closed though. It just doesn't have to be set as closely as the book wants.

Confusion? Read this: http://tinyurl.com/vxlnd

 

[Turbo. Targa. Life.]

WTF isa dash pot? I keep seeing that word used and I have no clue what it is...is that the big vacuum box at the passenger side of the firewall? I'll go check the IDL and E2 with the throttle closed though...

 

[OneJoeZee]

WTF isa dash pot? I keep seeing that word used and I have no clue what it is...is that the big vacuum box at the passenger side of the firewall? I'll go check the IDL and E2 with the throttle closed though...

http://en.wikipedia.org/wiki/Dashpot

It's the device that stops the throttle when you let off the pedal. It's on the throttle body. I don't have a picture of it on a 7M since I haven't looked closely at a 7M engine bay in quite a while. I'm sure you know what it is but probably didn't know it was called a dashpot.

 

[jetjock]

What Joe said. The dashpot keeps the throttle open for a bit after you come off it. Emissions device. It's the round gadget below the throttle body with the little hose and valve on it. Eases the throttle closed so some air is allowed past to burn left over fuel from when the throttle was open, thus limiting the hydrocarbon spike that would occur if the throttle were to be snapped closed. Truth is even when it's working right every Supra I've tested still spikes.

Dashpots come in many flavors and work on different principles but dampening motion is pretty much their job in life no matter where you find them. This particular type is reliable but can be a cause of idle problems (ie; keeping the throttle cracked and TPS off idle) if faulty or not set correctly.

 

[Turbo. Targa. Life.]

I wish I understood the language you speak JJ lol. OK SOOOOO, I tested E2 and IDL and at 0.0157" open I got 5.51kO (acceptable is "below 2.3kO" and at .0295" open I got 5.79kO (acceptable, again, under 2.3kO)

i dun get it :help:

 

[jetjock]

I wish I understood what you were saying . From what I see it's never going to work like that. Again, you either have a bad TPS or it's not adjusted right. Under 2,300 ohms means 2,299 ohms or less.

 

[Turbo. Targa. Life.]

lol JJ I'm glad you don't look at me like another noob asking a stupid question.

anywho I'm gonna try to find another TPS and see if that's the problem here. Thanks so much for all your help JJ. Invisible +1 and a cookie for you!!