1G Throttle body swap problems

[1990AWD]

I'm having some problems with my new throttle body. I have a 1990 GSX and put a 91-94 turbo throttle body on.

The Problem: I have a CEL come on when the throttle plate is closed for more than five seconds at a time. It doesn't matter if I'm driving and left off the throttle or idling. The second I touch the throttle, the CEL goes away.

When on the throttle, driving is normal - even idle isnt too bad.

What Ive done: I tried to check the CEL code. All I have is a DMM and its hard to read the pulses but I think its No. 14 which includes the TPS and closed throttle position switch. The throttle body is the only thing Ive changed so it makes sense.

I have the TPS set to .63V. Wires were soldered in according to colours.

I tested the ISC and all the coils are around 36 and 37 ohms. I know these are a little high, but I was told it was working. I also discovered there is a difference in wiring on the ISC between 1990 models and later models - the black and white wires are switched. I soldered them correctly according to colour.

I also have replaced the closed throttle position switch as the one that came with my rebuilt throttle body was not working. I have checked and adjusted it so it has conitinuity when closed and not when open.

I have been unsuccessfully researching this problem and will continue to but if anyone can help me, please do so. Thanks.

 

[gtbread77]

Pretty sure you know, but doesn't sound positive to me in your post. The 91-94 Throttle bodies are alot different, and that is why your throwind your cel. I think if you had link you could correct it, but im not sure on that somebody with more knowledge than me will have to answer that.

 

[1990AWD]

Well I think I wired everything in right so a later model TPS and ISC should act just like a '90 model, should it not?

Anyone else have any ideas?

 

[snowborder714]

Does this help?
http://www.dsmtuners.com/forums/newbie-forum/309791-can-you-use-93-isc-90-car.html

 

[1990AWD]

So even though the black and white wires for the ISC are in different pins from the '90 harness to a '92-94, I shouldn't switch them?

 

[snowborder714]

That's what I'm reading. I wish I had an answer for you though. If I think of someone who I know with a '90, I'll let you know.

 

[1990AWD]

I tried it both ways, wired by '90 standards and by '91-94 standards and the CEL is still there. It might just be something I have to wait until I get Link.

 

[1990AWD]

Update: I now have idle surge

I have the ISC wired according to the '90 wiring harness like you guys suggested, and most of the time I can stop the surge with a simple blip of the throttle. WTF is going on?

 

[snowborder714]

Damn, you have me stumped now.

 

[pantherballhp]

interested in this because i have a similar thing going on, mine is idling really high and my tach stopped working. i'm trying to narrow it down but i'm hoping its something simple

 

[1990AWD]

interested in this because i have a similar thing going on, mine is idling really high and my tach stopped working. i'm trying to narrow it down but i'm hoping its something simple

As far as your tach not working, have you checked that your noise filter is plugged in? It plugs into the harness underneath the intake manifold, by the plug for the knock sensor. My other '90 didn't even had one, grabbed one from a wrecker, plugged it in, and voila!

As far as I know, the tach on our '90 models needs that noise filter and the tacho interface which is attached to the ignition coil.

 

[pantherballhp]

I'm going to check the noise filter tomorrow. It has to have one cause the tach was working up until Saturday.

My problem with idle is a little different in that it's fine for about a minute and then the cel comes on and it starts idling real high. If I start driving it it'll start idling fine again for ab 30 seconds. But I'm pretty sure my prob is vacuum leaks.

 

[1990AWD]

I'm going to check the noise filter tomorrow. It has to have one cause the tach was working up until Saturday.

My problem with idle is a little different in that it's fine for about a minute and then the cel comes on and it starts idling real high. If I start driving it it'll start idling fine again for ab 30 seconds. But I'm pretty sure my prob is vacuum leaks.

Well all I can say is check everything.

1. BLT.

2. Ensure your throttle position switch is working and adjusted right. There should be continuity between the sensor and ground when closed and none when throttle is open.

3. Adjust TPS to .48-.52V when throttle is closed.

4. Check resistances of ISC. They should be between 28-32 ohms.