No cat

[ysteve]

Hi BOB Naylor, hi guys. Ijust remove my cat and put pipe. And my shifting and power little bit improved, but not everything. I know i am piss you off with bunch of questions, but we really cant find problem. And problem is missfire. I have two questions: 1st After long of driving my fuel pump little bit noise, i can try to open and clean it but i dont know if it can cause it. 2nd Can cause this 1st oxygen sensor with no codes. And last one, how i can check my injectors for continuity, connector near the alternator is have a lot of legs. I thought it suposed to be 12 but looks like more, Alldata dont have this info. And maybe you can came up with more ideas, what can cause missfire. Steve 3.4, 86000, fuel and air filter, plugs and wires, MAF,PCV.
Thank you so much.

[maxwedge]

Do you feel a noticeable misfire and if so under what conditions? Any codes for a misfire also?

[ysteve]

No codes. Engine shaking on just ideling.

[BNaylor]

I've got to give you credit you are persistent and not ready to give up but that is good.

Are you 100% sure you do not have a vacuum leak? Check all vacuum line connections in and around the intake manifold. A loose or cracked vacuum line will make the engine shake and have a poor idle with no misfire DTC error codes or SES light. Did you ever test your engine vacuum?

To ohm out the fuel injectors you can do it at that connector plug unless you prefer removing the upper intake manifold to access the fuel injectors but you'll need the color coding and pinouts from the service manual for your year Impala. Fuel injector coil resistance should be around 11.4 and 12.6 ohms.

Let us know yor findings. Good luck!

[Gems]

On my 3.8L engine there is an IAC valve (idel air control valve) mounted on the throttle body next to the MAF sensor... I pulled the IAC valve and it was all carboned up... I did a real good cleaning job on it and noticed an improvement in idle smoothness...

Not sure if the 3.4L is set up the same way...

[ysteve]

I just check vacuum 17-18in. On top post i tolld you about fuel pump, that i have wining after long trips, can i clean it some how or maybe something wrong with it.(cause like i asume we have filter only after pump not before) But pressure i have 52-53 psi. And another question what symptoms malfunction oxygen sensor(1ST), and does it gonna trow a code?
And i did some reserches and find that harmonic balancer can do missfire too. Does anyone had this problem(balancer) on 2003 with 86000m.
About colors on connector(injectors), where i can find them, alldat dont have that# C102(16 cavities). And i dont have manual.
Thank you for info/

[ysteve]

Somebody have info about IAC. Cant find it. I open mine looks real bad, maybe that causing my problem. I need model number, and where i can get it.

[BNaylor]

Originally Posted by ysteve

Somebody have info about IAC. Cant find it. I open mine looks real bad, maybe that causing my problem. I need model number, and where i can get it.

They always look bad. It accumulates a lot of soft carbon. Just clean it first. Use carb or throttle body cleaner on the spring loaded pintle. Then clean the seat where the IAC mounts to the throttle body. There is an air passage/orifice on the TB side that can clog up with the soft carbon. Clean the inside of the throttle body. Try that first and if it doesn't help let us know and we'll go from there.

[ysteve]

Hello guys. I have two good news. 1st i paid my car off. 2nd after cleaning IAC, now llitle bit better, but still like missfire. I wanna buy new IAC cause when i start clean it spring and pin fall off. Then i notice the pin have a treads, i screw it back. After all job done i had problem to start the engine. I just wanna replace it, i dont wanna play around with that. I need model # and where i can get it. Satturday i try to check my compression, i got that gage. One question beside this. What functions of air intake temp. sensor. Probably i am gonna try to change bunch of sensors. About IAC, i never saw such a dirty parts. I have better power now but not at all, my shifting is anoing and think that because of missfire. If somebody have connector colors for injectors i would be apreciated.
Thank you for reply.

[BNaylor]

Originally Posted by ysteve

I wanna buy new IAC cause when i start clean it spring and pin fall off. Then i notice the pin have a treads, i screw it back. After all job done i had problem to start the engine. I just wanna replace it, i dont wanna play around with that. I need model # and where i can get it. Thank you for reply.

The IAC is GM part # 17112350, list $118.45 available at a GM Dealer.

AZ has Wells brand part # AC107 for around $40.00.

[ysteve]

What is AZ?

[BNaylor]

Originally Posted by ysteve

What is AZ?

Autozone

[Gems]

Originally Posted by bnaylor

The IAC is GM part # 17112350, list $118.45 available at a GM Dealer.

AZ has Wells brand part # AC107 for around $40.00.

That's a big price difference between the GM part and the AZ part!... I'd be concerned about the quality of the cheap AZ part...

[BNaylor]

Originally Posted by Gems

That's a big price difference between the GM part and the AZ part!... I'd be concerned about the quality of the cheap AZ part...

I agree but the GM list price is inflated. GMPartsDirect.com has it for $61.59 but there will be a shipping charge and waiting time for the part. I used a Wells brand IAT sensor before and it worked.

Sounds like YSteve needs one sooner since he messed up the IAC.

[ysteve]

Guys like i tolld you before, i am gonna change bunch of sensors. So here you go: Yesterday i order(from GM) folowing: PURGE CONTROL VALVE, AIR INTAKE TEMP. SENSOR, PCV, IAC, MAP SENSOR. It was around 200$. This parts gonna be delivered on friday. Satturday iam gonna install all this and gonna respond. If this not gonna work will go farther. Then i have to change rest of sensors, and i am gonna need your help to figure out wich ones. You now i dont care about money right now, i just want this done. Whatever it gonna cost me. I am pissed alredy bacause no power and hard shifting.
What you think, this cant be mounts, right?(about hard shifting)
Can it be Oxygen sensor(1st)? (about no power)
Thank you BOB and GEMS.