I've been having a cold start problem with my engine for the longest time and it doesn't seem to matter what I adjust, it doesn't get better. I'm running ARAP code on a somewhat modified engine and I have the fuel pretty close and have no spark knock. Once the engine warms up to closed loop it runs fantastic. Open loop is another story. The engine seems to be lean in open loop, but I've gradually richened up the mixture until I can smell raw fuel out the tail pipe.

When I first start the engine when it's cold it'll fire up great, stumble, die. On restart sometimes it'll chug for about 20-30 seconds then smooth out. What's strange is, it won't idle up to what I have the "idle speed vs coolant temp" chart set at. For example if it's 20 degrees outside and I have the idle set to 1200 rpm, it'll just sit at 650. The odd time if I help the idle come up with my foot on the gas pedal for a minute or so and let off it'll hold the idle up for a wee bit.

I've adjusted 'crank fuel vs temp', every spark chart, the map tables, the map scalars, and I cannot get a nice smooth start with the engine revving up to what the 'idle speed vs coolant temp' chart states.

If I run AUJM code the starts are better even if I copy my current fuel and spark tables from my currently running ARAP bin. So why not just run the AUJM code then? For some reason I still have more power with the ARAP bin despite identicle spark maps, fuel maps, and scalars. I'm frustrated with it and am getting tired of having to hold my foot on the gas pedal until the engine warms up.

Thanks for the help,

-Howdy

 

What program are you using to tune with. Definitly sounds like a fueling problem. There should be open loop fuel tables to adjust. Make sure your IAC valve is clean and check the motor windings with a multimeter. Im using TunerPro for tuning and datalogging give that a try if your not already using it.

 

I use tunerpro to tune with and winaldl to datalog. I tried datalogging with tunerpro but it won't talk to the ecm. I'm building a max232 cable and hopefully that'll resolve that issue.

I agree with you that I have a lean problem but I don't know what table or tables to adjust. I was under the impression that while in open loop the fuel delivery is dependant totally on the MAF tables. Are there other tables I should be adjusting?

-HD

 

"Are there other tables I should be adjusting?"
Yes, like i said look for the open loop tables and monitor your coolant temps and adjust accordingly. Make sure your using the 6E xdf file mark included with TunerPro and you should be seeing improvement in no time.

 

The only tables I found pertaining to open loop in the 6E code is the "Open loop AFR % Change vs. LV8" and "Open loop AFR Ratio % Change vs. Coolant Temp" tables.

I added 20% across the board to the second table. I noticed no starting improvement and I actually suffer worse lean conditions in open loop with a hot engine. Did I go the wrong way with the numbers? I guess I don't understand exactly what these tables do and what they calculate and how it effects fuel delivery in open loop. Can anybody explain more what these tables do? I'm always nervous adjusting values in tables when I don't know what they do.

-HD

 

Never overlook the obvious, are you absolutely sure everything mechanically is right?.

Might double check you IAC/ min idle setting.

 

I will check the min idle air again but don't see how that would contribute to the lean open loop condition I'm having. I could see how that might have an effect on the engine not idling up on cold start, but not the lean condition.

 

Are your injectors new? I had the same problem, and i refused to blame it on my injectors, but it was all i had left to check, so i had them cleaned, as well as the throttle body, after that my cold starts were amazing, it would fire right up no problem at all, i did not have to keep it running with my foot on the petal until it ran by itsself. Maybe its worth a look?

 

Are your injectors new? I had the same problem, and i refused to blame it on my injectors, but it was all i had left to check, so i had them cleaned, as well as the throttle body, after that my cold starts were amazing, it would fire right up no problem at all, i did not have to keep it running with my foot on the petal until it ran by itsself. Maybe its worth a look?

 

i had this same problem, i cleaned my injectors and throttle body and it was amazing how good it started and ran on open loop. Maybe not your problem but worth a shot? I always had to keep it running by holding my foot on the gas until it got into closed loop.

 

i had this same problem, i cleaned my injectors and throttle body and it was amazing how good it started and ran on open loop. Maybe not your problem but worth a shot? I always had to keep it running by holding my foot on the gas until it got into closed loop.