Tranz Zam

The car seems to have an issue with idling. I took it out today and got a hard brake pedal so I figured it was the cheap booster taking a dump, but it turns out the little check valve that the hose connects to was broken. So I replaced it with a used one I had in the garage and now the car doesn't want to idle.

I ran the scanner on it and it say there's no codes. I'm assuming its a nasty vacuum leak but I could use some other ideas on what to do. I checked the intake bolts and they're tight. The vacuum line running to the trans is on and tight. The throttle body is tight. The intake has all new gaskets.

If you start it and give it some gas it runs smooth as silk. Sometimes it'll even idle on its own.

Its a LQ4 with a TH350 behind it.

HwyStarJoe

Forgetting the brakes for now, If you disconnect the line from the booster and plug it....does it idle?

Tranz Zam

Negative.

The port on the back of the intake wants to move (spin) around. It's been awhile since I've had the intake off but I don't remember that wanting to spin. I'll pull the intake off today and check it out. Im thinking maybe I cracked it when messing with the booster line.

Tranz Zam

I pulled the intake off and the two rear-most intake gaskets looked blown out. I replaced them and the car seemed to run better for a while.

Now it doesn't want to idle in park when cold, and has a hard time starting. I got code P0507 which is an IAC code.

It seems that when most get this code they experience high idle, but I have the opposite. Do you think its the IAC itself?

Tranz Zam

I grabbed a few IAC and TPS out of the junkyard today. I replaced the IAC, still nothing.

I also got code P0154 and P0134. Those are both 02 codes. I replace the Dr Side because it only came up with one code, but now its saying the pass side isn't reading.

Any ideas? Is it possible theres a pin or wire that moved around that goes into the computer?

Tranz Zam

Also, the throttle isn't as snappy anymore. If its in park at hot idle and you snap the throttle real quick it'll act like it wants to stall. The exhaust is dumped and there seems to be a lot more condensation/fuel on the ground. Theres also a steady flow of exhaust "smoke" like what you'd see during the winter, except its 65F out and the cars fully warmed up.

I could really use some guidance here guys.

DW SD

Not sure what you mean by "dumped" on the exhaust. If you have open headers is it possible the O2 sensor is also measuring air making its way in the header? Perhaps the engine is adding fuel based on thinking it is too lean?

Are you sure the intake gasket isn't blown out again? Vacuum leaks cause a lot of issues. P507 seems to indicate vacuum leak.

Tranz Zam

Dumped is just another term for turned down. It runs off the headers into two mufflers, then turns down before the rear axle.

It turns out the o2 I bought is the wrong one. I knew it had the wrong connector (triangle) but I figured I could re-pin it into my old connector (flat). But as I'm reading now it seems like the 99-02 flat connectors are grounded through the exhaust while the newer ones are grounded through the pcm. Unless I read wrong?

So I assume the Dr side o2 that I replaced isn't doing anything. I found the correct flat style o2's on ebay. Nobody around here seems to have the flat connector style.

Would having the wrong Dr side 02 cause the passenger side not to read correct? As soon as I replaced it the passenger side threw a code, but it never did before.

DW SD

are you sure you don't have another vacuum leak. sounds like you created the new code issue on the wrong O2 sensor.

Taxman20

iTrader: (11)

Easy way to locate a vacuum leak. Spray shots of carb cleaner in spots around intake and vacuum ports and if it revs up then that's a leak. Check all around the intake, ports and even the brake booster.

Tranz Zam

I'm not positive that I got rid of all the vacuum leaks. I'll check.

I'll do this. Whats weird is the car just made a 70 mile journey earlier in the week, but now it doesn't want to move.

Chicago TDP

iTrader: (3)

Sounds like another vac leak.
Put a vac gauge on the intake after the throttle body....check that the vac is "good"
I had a vac leak one time when I had an aftermarket throttle body on a stock intake.
There is an adapter plate that is needed with some throttle bodies.

Tranz Zam

I replaced both o2s and it seems to be running much better. I still need to hammer out the tune completely, but its much much better. I'll still go over it checking for vacuum leaks.

ijimmy

It could be an exhaust leak also check everything from the o2 sensors to the engine , and the 02 fit

Tranz Zam

There's a small pin-hole leak about 5" behind the passenger o2, right where the H pipe splices in.

The car runs normal again after the o2 swap. On a side note, would running a 4lb bigger set of injectors un-tuned for almost a year kill o2's? I figured its not doing them any favors. I went from LQ4 injectors to 04 LS1's.

Tranz Zam

Well the problem is back. I'll check for vacuum leaks today and see what the deal is.

It starts like total **** when its cold. You need to keep it idling on your own until it'll catch. It also sounds a little more "choppy" at idle when warmed up.

The odd thing is theres no codes.