Okay guys Ive been having idle problems and a surgung while driving problem for a while, so a last wednesday I took my throttle body off and rebuilt it using a GP sorenson kit. Besides the grunge nothing looked broken. I ended up not doing the adjustable fuel pressure mod. I took the IAC out and ejected the pintle, cleaned it up and gently sprayed a little carb cleaner on the part where the pintle screws in (probably a bad idea...). I went to start it up and it wont start, it cranks, but it wont start. I gave it a little gas and it starts but runs like crap and wont stay running unless I keep my foot on the gas, it will instantly die if I take my foot off the gas.

I jumpered the A and B ports of the aldl and it showed a code 12... what is that?

I suspect that the problem is the IAC, I turned the key into the on position and went and peeked and I could see the pintle protruding out from the top of the throttle body... shouldnt have it retracted some? What if I have someone crank the engine while I look, should the pintle retract and allow some air to pass by it?

I tried disconnecting the battery to reset the computer, but it did nothing.

 

First are your Injectors dumping fuel like they should? If not you might have put the TB back together wrong ... check fuel lines and delivery. Could be a bad pump if your not getting fuel. That would explain the stumble before you rebuilt it. Code 12 means the computer is working just fine. Very well could be the IAC too. Maybe you put it together wrong after cleaning.

 

The fuel pump was replaced less than 1500 miles ago. When I first tried to start it fuel was spraying out from around one of the injectors, I isolated that problem to a oring, fixed it and now no fuel leakage. Injectors look to be squirting fine... a pulsating cone spray of fuel.

The IAC does not move when someone is trying to crank the vehicle.

I sure hope its the IAC, cause I just had them order one at the parts store. AC delco... cost $50. It will be here at 4pm

 

Yeah, from the sound of things it's your IAC. When you crack the throttle more air is getting let into the engine but there's still too much fuel so it sputters. IAC controls idle and a lot of other aspects that people dont pay attention to. Post up later if it fixed the problem. I'm curious to see .

 

We'll also see if it fixes the high idle and intermitten sputter, where it also feels as if the car is "hiccuping" occasionally as you drive. Which was the reasoning behind the throttle body rebuild.

 

Installed the IAC and the car started right up.

Fixed that problem, but did not fix the surging problem. I cant figure out what is causing this, but as Im driving along it feels like the car sporattically misses or "hiccups" as I call it. I tried to pull codes and theres nothing. Seems like it only does it at less than 3000 RPMs. I can tromp down on it and doesnt do it. This is driving me crazy and keeping me broke.

I will replace the entire car if I have to to fix this!!!!!

But besides that I can tell the TBI rebuild made a big differance, the car is alot smoother. Throttle response is much better.

 

Glad to hear you can get your car started again. I'm at a loss of what it would be next.

 

Could it be a TCC problem? Hard to tell by just your description, but it sounds kind of like harsh TCC lockup.

 

I can be steadily cruising at 55-60 in 4th after lockup and it will hiccup about 10-20 times a minute.

Could something grounding out cause this?

 

My mom's 94' Roadmaster did this exact same thing, and after changing the plugs and wires solved the problem.

 

Good call roadmasster. Because of your post I decided to take the cap off and inspect it. Inside it looked pretty bad, it had pitted contacts. Never suspected it because it "looked new".

The car still idles a little high, but overall runs MUCH better. Thanks guys

 

Sounds like what my 91 was doing before I had a diagnostic and they replaced the EGR valve. That cost me 400 so I suggest you change it out yourself.

 

Did yours idle slightly high? Did the surge clear up when it got warm?

 

I could be sittin at a red light foot no where near the acc and the engine would rev itself up and bog down and die.

 

I do not have that problem. When I start mine up it revs itselfs up, then bogs down and before it dies it revs up again. Only does it for like a minute during a cold start.