Rough idle and dies when I put it into driver or reverse

aarroyo87 · 10-21-2009, 12:48 AM

I have a rough idle and dies when I put it into drive or reverse. The idle surges about 125 RPMS give or take. The engine constantly hunts for the desired RPM while in park. The symptoms are similar to a vacuum leak but i don't think I have one. I want to smooth out my idle and fix what ever is causing it to die when I shift my transmission into drive. The car drives great. The problem only happens at stand still for while braking. This is my setup.

New plugs and wires – not burnt or fouled
New opti
New TPS
Cleaned MAF filament
No vacuum leaks. Searched by spraying engine start around the engine
I have a solid fuel pressure. I checked while driving and it stayed between 40 and 47 PSI
New fuel filter
No arc’s in wires – checked at night
Bored out 52mm TB – bought from eBay remanufactured
No EGR. I have a block off plate
No Cats

I have Freescan so I can provide logs also. Any suggestions?

shbox · 10-21-2009, 08:05 AM

Make sure your PNP (Park/Neutral Position) switch is working. Not sure about Freescan, but most scanners will detect the gear selector position. The computer adjusts idle when in gear or not in gear.

aarroyo87 · 10-21-2009, 11:08 AM

Rob, I did not even think of that. I'll look at that today and get back to the forum with an update.

aarroyo87 · 10-21-2009, 04:44 PM

So the switch was part of the problem. I had it hooked up to the switch that was always grounded. I switched it to the proper wire and adjusted my park neutral switch. That part is now working fine.

I still do have the problem of it having a rough idle and sometimes dying when shifting into drive or reverse. The switch is accurate now cause I tested it with a multimeter. It gounds out in park and neutral and ungrounded in all the gears. I know it works also because the desired idle speed changes from 800 in park and neutral to 750 in all the gears. I'm pretty sure that is the way it suppose to work.

My IAC moves and tries to correct the idle speed. I can see the position change on my laptop. I heard that I can reset it some how. I'll look into that.

I am noticing a rich gas vapor when it dies. I think I will check fuel pressure again.

aarroyo87 · 10-21-2009, 04:57 PM

Fuel pressure looks good. 46 PSI at idle and 50 with the vacuum unplugged.

aarroyo87 · 10-21-2009, 05:05 PM

Recap.

New plugs and wires – not burnt or fouled
New opti
New TPS
Cleaned MAF filament
No vacuum leaks. Searched by spraying engine start around the engine
I have a solid fuel pressure. I checked while driving and it stayed between 40 and 47 PSI
New fuel filter
No arc’s in wires – checked at night
Bored out 52mm TB – bought from eBay remanufactured
No EGR. I have a block off plate
No Cats
Rewired and checked park neutral switch
Double checked fuel pressure with vacuum off
Holds fuel pressure at 46 for quite a bit of time

Any other things I should check?

Could it be that my IAC moves too slowly or sluggish? Hmmm?

Suggestions anyone?

aarroyo87 · 10-21-2009, 05:09 PM

Oh ya, I checked grounds too. I have the motor grounded to the battery and there are straps from the motor to the firewall and radiator support and frame.

Black96transam · 10-21-2009, 11:22 PM

the MAF could be going bad itself.. my buddy blazer done that.. it would run for a few secs then start hesitating.. changed MAF now its fine

aarroyo87 · 10-22-2009, 12:20 AM

Is there a way to test the MAF? Cause I do not have access to an extra one. I guess i can find one but that might take some serious part chasing.

Black96transam · 10-22-2009, 12:28 AM

i think so.. but you might wanna check shbox's site on that..where are you located? i have 2

shbox · 10-22-2009, 07:47 AM

Quote:

Originally Posted by aarroyo87

Fuel pressure looks good. 46 PSI at idle and 50 with the vacuum unplugged.

I would say that is a little higher than normal. Your idle pressure is higher than what it is supposed to be with the vacuum line off. Most people's idle pressure is a bit less than 40 and 41-47 unplugged. Might not be an issue, but since you are still searching...

koolaid_kid · 10-22-2009, 08:19 AM

I agree about the fuel pressure. The "perfect" pressure is 43.5, which you will seldom see unless you have an adjustable FPR. It should drop a few when the vacuum line is reconnected. If you'll check the sticky at the top of the Fueling section, you'll see that 50 psi (using 24 lb. injectors) will actually make them closer to 26 lb. at that pressure. This will make it run a bit rich, since the PCM believes it is fueling 24 lb. injectors. Just something else to verify.

BOLO · 10-22-2009, 11:01 AM

Is it throwing any codes? I recently had a similar issue with car wanting to stall when put on load( on gear reverse or drive). It was throwing a dtc33-map sensor. End up to be a simple wiring issue. I'd double check on all wiring/electrical connections. Good luck.

aarroyo87 · 10-22-2009, 11:48 AM

I'm located in San Francisco CA. Looks like you are in IL

FYI - I'm running 30 lb injectors and a 52mm TB, 1 3/4 header and lloyd elliot le1 heads and mild custom cam. The PCM has been base tuned for 30 lb injectors already. The fuel pressure might be a little too high. When the car is about to die, I do smell a gas vapor and it stings my eyes. I also noticed that my Lterm or BLM is a little low. Are the stock regulators adjustable?

I'm going to the wrecking yard today to see if I can find a clean MAF and maybe another regulator.

No codes yet.

red-_-z28 · 10-22-2009, 12:44 PM

unplug your maf and then see how it runs..

aarroyo87 · 10-27-2009, 11:47 AM

I unplugged my MAF and it still has the idle problem. I replaced my LT1 knock module with an LT4 module. I needed to do that anyways and i did not expect it to fix anything during idle.
I do have off brand O2's in there. They are new but not the recommended brand. i just ordered some AC Delco's and they should be coming in this week.

Here is a datamaster log file. It starts with a cold startup then end after a 14 mile drive.
http://www.4shared.com/file/14410243...dleNormal.html

Slvr00Bird · 10-27-2009, 12:32 PM

Sounds like a cam sensor..

slow96z · 10-27-2009, 02:34 PM

I keep seeing new wires and new opti, did this start immediately after the installation of the new opti? Is it possible the wires are out of order? I know that happens alot.

whammer33024 · 10-27-2009, 03:42 PM

sounds like something similar to what i had going on...try unplugging your o2 sensors and see what happens

BlownEarDrums · 10-27-2009, 05:56 PM

I seccond the o2's and the cam sensor. What Opti did you use?