Hey guys,

I was screwing around with my idle maps a little bit, to lean it out and lower the idle in an attempt to save gas. I didn't get the results I was hoping for and I think this has now caused my car to have difficulty starting (stupid, I know). The car used to start up perfectly, but after a few tweaks (up and down a notch or two on the 30"- 0" idle maps) the car will still start, but it is struggling to do so. I have to hold the starter for a lot longer and give it a little gas. The motor will kick a few times (sometimes popping) and finally start and stumble for a bit, until I give it a bit of gas, then it will smooth out. I see a decent amount of smoke on initial start, as if the motor was almost flooded. I can see my AFRs slowly drop from 14.8:1 on initial start down to 11.5-12:1 idling the whole time.

It starts no problem when it's warm...this only happens when the car has been sitting for a while/over night. I did not touch any other settings, aside from tps_scal when the car was completely warmed up. I can post my current maps and any other info you'd like later tonight.

Can someone please post a baseline idle map for 4x 750cc injectors? Or help me tweak mine? I'm not even sure if the idle map has anything to do with starting, but I remember hearing so.

Specs:
88 TII w/ streetport
LT8
4x 750cc injectors

Any help is greatly appreciated.

Thanks in advance,
Jaime

 

mess with the water map

 

since you remove fuel from the idle map you need to compensate with more fuel on the water map at the lower temps like flaco said.

 

Thanks for that!

 

yea, with some setups it can only take as little as 2% change to lean out to the point where the engine doesn't like it, but this is usually a hot start/idle issue concern. when cold most maps are plenty rich, could be an indicator of other things like injectors leaking down or fuel pump taking too long to prime.

i'm not steve, i don't dump fuel into the maps so even a little leaning out usually results badly with the engine running/cruising. try bumping the figures back up a little, keeping note of your starting points and your adjustments made. if nothing seems to help then you may have to look at other things like cranking fuel pressure and possibly having the injectors tested again. some engines just will never really get good gas mileage(like Nick's), not sure why there is such a variance with these motors but some run hot, some run rich, some just don't ever want to run.

in all reality, injectors should be tested and cleaned every few years on these engines pushing at or over 300whp. i believe they are going on 5 years now?

nothing really stood out too much in the maps but there was a few areas that did look a little lean sided such as idle map 0-10"Hg which is used during cranking.

backfiring during cranking is somewhat normal with the microtech but it is because the microtech doesn't filter electrical noise very well. basically speaking the noise from the starter pulling power causes noise in the whole car, the CAS wire shielding is insufficient. you can try closing the CAS sensor gaps a little and it may help, or ground the CAS loom shield wire if it was one of the ones that microtech did not. another issue is weak spark during cranking, do not use platinum plugs as they foul out in these motors and the microtech has a tough time firing them cold when they are borderline fouled with premix. a weak battery will also give a mix of everything above with weak spark, slow cranking speeds and hesitation to start so try throwing a charger on it for a bit or have the battery tested.

 

Thank you SO much Ben. I'll try small things at a time, but I think it might be the fuel pump taking too long to prime, like you said. I noticed that if I left the ignition on for a bit longer, before cranking, the motor would start a little easier. I'm using BUR9EQs all around, so no platinum. Actually around 4 years with these injectors, I think, since I swapped out the Venom ones with FIC ones. I'll give them a clean as well.

I'll give everything you noted a shot and will post back.

Thanks again for your continued support!

 

if i remove gas from the load map should i add on the water map?

 

no. if you add on the watermap will add everywhere . so what ever you did with the idle map just play with the idle map again leave the rest alone