85whtz28

I have been at this for a while now, I am having trouble when the car is cold it has an irratic idle and surges when put into gear. When you press the gas it backfires through the intake a couple of times then takes off. It runs strong from there. Once the car is warm it does this intermittently. I also get a little roughness at highway speeds and the motor is revving between 2200 and 2700 rpms. Also it is not throwing any codes. The motor was rebuilt in August last year. Smog system and cat removed.

What I have done so far is replace the fuel pump, sending unit, fuel filter, TPS (voltage 4.5v), IAC re-set 450 rpms, new plugs, wires, cap, rotor, vacuum lines, intake gasket kit, injectors, O2 sensor, water temp sensor, and knock sensor. I have also tried tapping on the MAF to see if it changes. Timing is set to 6*btdc. I have a new MAF sensor and intake air temp sensor coming in tomorrow. Any other ideas if those do not fix it? Anything could help, I am at my wits end. Thank you

305sbc

iTrader: (3)

Hook a vacuum gauge up to it and see what it is doing.

irocarter

iTrader: (1)

It's probably not your problem but, I thought automatic cars should have the timing set at 8btdc and 6btdc for stick cars.
What cam are you running?

skibum2100

I think I found your problem, the TPS should be .54V...

I hope this helps.

85whtz28

I think I figured it out, my IAC and MAF were causing it. It was running real bad yesterday, so i pulled the IAC connector and it idled up. Got the MAF in and changed it and went ahead and changed the IAC too. Seems to be running a lot better. My TPS is now set to .54V and has pretty good response now. Thinking an AFPR is coming next. Gotta make sure its running right, then let the mods begin
Thanks for your help

85whtz28

Well it ran good for a day now its throwing code 43 Anyone know where to start with this besides maybe a large cliff?

skibum2100

Code 43 pops up every time I set the timing, you have to reset the codes in the ecm. Make sure the single connector brown wire is connected (above the heater box under the hood, pass. side).

Hope this helps.

85whtz28

well I started backwards and checked my grounds and tried manipulating the ecm to see if I could find the issue there, nothing. I read on here somewhere that fuel pressure can cause a knock sensor fault. So I checked fuel pressure at the rail and I am only getting 32 psi. Anyone know what voltage I am supposed to get to the fuel pump? And any other ideas to increase my pressure?

skibum2100

You should have a full 12v at the pump and 32 is low, it should be 43-47psi. Your FPR diaphragm could be torn, pull the vacuum line to the FPR and check for gasoline.

85whtz28

Ok i replaced the fuel pump again, thank god for warranties. I clamped the return line and tried to build 85 to 90 psi up with fuel pump. It only jumped to about 40. So i knew it wasnt the FPR. now i still have a little roughness at 2200 rpms.

skibum2100

Do you have the proper fuel pressure now (~45psi)? If so, you should consider a scanner (you can build one at home from a laptop and a trip to RadioShack->do a search for WinALDL), a scanner will tell you alot more about what is going on at 2200rpms and maybe we can see a pattern, indicating a problem.

Hope this helps...

85whtz28

yeah, i got a fuel pressure gauge and i am getting about 45 psi. I still get a lean exhaust code everyonce in a while. I think I may just need a AFPR to be sure I am not losing fuel pressure while driving.

skibum2100

Glad you got one thing sorted out...you could drive around with the fuel pressure gauge taped to your windshield (I did this just to verify that I wasn't loosing fuel pressure at full throttle).

The Lean Code can be caused by many different things. The lean code can come from: an exhaust leak, a continued low voltage from the O2, a missing bias voltage from the ECM, etc...lots of potential causes for this.

I will attach somemore info for this code when I get home...what code exactly?

Good luck.

85whtz28

I do have a small leak on the passenger side manifold, but wouldnt think this would be enough to throw a code for an O2 sensor on the driver side manifold.

skibum2100

You are right to think that a leak on the pass side won't through this code. Put a multimeter on the wire for the O2, you should have 451mV. If not check your grounds, including checking the continuity to ground of the exhaust manifold (because the O2 circuit relies on the ground through the exhaust manifold and into the engine grounding strap).

Hope this helps.

And here is some info for the lean code (code 44?).