LVJimmy

Had my computer tuned and it idles at 1600 with 29 degrees of timing. If I rev it up to 4000 the timing goes to 44 degrees. The engine is a stock '04 LQ4 from a van in a 70 blazer. The tuner claims this is normal timing on these engines. Does this sound remotely correct?????? I'm assuming the advanced timing is causing my high idle problem.

Pro Street

iTrader: (3)

How are you checking timing?

wait4me

iTrader: (10)

Depends on the KPA of the engine. under light or no load it is possible the timing will be that high, But under load, higher than 50ish kpa, it shouldnt be that high at all. Usually at 80+kpa it should be 22-29degrees..

LVJimmy

I initally checked it in park. I have since driven the vehicle and the timing still goes up to ~29 degrees at 1600 rpm but I still haven't really put any kind of load on the engine. I'll try again today and see if its' any different.

Thanks,
Jim

LVJimmy

at least i now know I'm not melting my pistons. I'll drive it again today and see what happens.

Thanks,

LVJimmy

In drive under a load timing drops way down . Engine still misses, runs poorly and idles high. The Predator still shows 5 different codes:

P0101-MAF
P0315- Crank Shaft Position Not Learned
P0507- Idle control system, RPM higher than expected
P0522-Oil Pressure low (stock oil sender isn’t hooked up)
P2761- Minimum Idle Position not Learned

JL8Jeff

iTrader: (14)

I see 41-44 degrees of timing while cruising so that doesn't seem to be a problem. At idle I think it's lower like around 19 but I'll have to check again to be sure. The crank code sounds like the crank sensor isn't hooked up or working at all. And the idle sounds like the IAC may need to be cleaned in the throttle body or checked to make sure the IAC motor is working properly. Start with the crank sensor and see if you can find out why it's not reading anything, that could be messing with the timing and idle.

P Mack

iTrader: (6)

No, the timing is not causing your high idle. You can put the timing to 45* at idle and have it idle at 800 rpm if the IAC is doing its job, i've done it. It's either something else in the tune that was changed, or something mechanical like a vacuum leak or throttle body not closing all the way.

wait4me

iTrader: (10)

Go to www.efilive.com and download the free trial version of software. Then open up a supplied tune or one from the website, and look at the spark tables, you will see what they look like stock..

LVJimmy

The IAC is good. I swapped it with a known good one. Mine still idles at 1600 theirs 700 rpm. don't think it's a vacuum leak either besides spraying carb cleaner everywhere I put tape on the plunger of the IAC and it idles at ~450 rpm. Visually and according to the predator the throttle body is closing all the way. I'm thinking that the computer isn't signaling the IAC to operate. I tried to call Curent Performance, who did the tune, but they are out of the office until 1/7/08. You think they might have said something about that when they shipped my computer back just before Christmas. I should have a chance to work on it today since things are getting back to normal.

P Mack

iTrader: (6)

Ok, the Iac is good but it's not doing what it's supposed to. Usually that happens when the throttle is just a little bit open (because the screw is adjusted too high), but enough that the pcm thinks you're holding the throttle open on purpose so it never goes into "idle mode" where the iac adjusts to get you to idle rpm. I don't know if that's your problem because of the missing and the codes though.

LVJimmy

I have already backed the screw out and made sure the cable was loose. I also made sure it was althe way closed by hand. Nothing has changed. I think that I'm stuck waiting for "Current Performance" to come back from vacation.

LVJimmy

The computer was not set up for the IAC. There was some confusion about the TB that I was using. I sent it back to Current Performance who worked on it and finally switched it with a different computer. The truck now runs 10x better then before.