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idle-part throttle migraine.

F

fastcomet

Member
Joined
Oct 5, 2016
Here's my car
91 240-AW71-19T (20lbs boost)-3 inch ex.- Boost gauge-AFR Gauge- E85- 650cc injectors- 3 AMM.-NPR- 3.73 gears-NLAO chips
Problem- After car warms up. IT will die after letting off fuel at low speeds. Then its hard to start like its flooded.
What I have done to try and fix problem- Checked and replaced IAC- Adjusted then replaced TPS- Ran codes all checks our good now.- Tried 3 different AMM- Put it back on gas with same results- Replace 02 sensor- Replaced coolant sensor- Tried different ECU AND EZK- Double checked my AMM solder job- Tried 2.5 bar FPR no change. New plugs-wires-dist cap.-New coil. Car runs great others wise and EFR numbers are in check.

thoughts------Could speed sensor be causing problems? Noticed today when it dyed the speedo needle was jumping around right before it died.-My injectors are a 4 hole injector, could they be causing problems? Came with flow sheet and they are not elcheapo injectors. Again I ran codes today, came out good. I tried the ghetto idle check valve but have same results. Thanks for taking the time to read this post. The car kinda did this before all the mods, I figured it was a bad AMM, but it seems to be getting worse with time. Thanks
 
My wagon does about same thing, but without the hard staring issue, and at pretty much any temperature. What does your wide band read when it does it? I wanna blame my issue on the speed sensor but I have to fix that to be sure. Don't worry about 4 pintle injectors causing you to stall, it's likely something else. I'm running single pintle injectors with the same issue
 
The AFR are on the lean side when it happens. Readings of 15-16 but when you step into the throttle it comes down real quick 12s. So how do you fix the speed sensor? Is there a way to bypass it? I put a smaller AMM on it today, still does it. :grrr: Hope someone chimes in.
 
Hi

my best guess would be that the chip is not converted to 3" AMM.
You should ask the supplier if it has the correct parameters to run a 012 or 3" AMM.
Just putting a larger AMM on a "stockish" tune will confuse most if not all parameters in the LH system.

YS
JB
 
I thought that too. But I’m now running the small amm. Still
Does it but will say over all it does run better with the stock size but still stumbles and dies on occasion.
 
Did you actually clean your throttle body, or just the stuff you mentioned? Clean it if not, reset the base idle(clamp off the IAC hose) for 750rpm, recheck your TPS adjustment after that and see what happens. Also obviously, make sure there aren’t any vacuum/boost leaks.
 
klr142 said:
Did you actually clean your throttle body, or just the stuff you mentioned? Clean it if not, reset the base idle(clamp off the IAC hose) for 750rpm, recheck your TPS adjustment after that and see what happens. Also obviously, make sure there aren?t any vacuum/boost leaks.
Click to expand...

-Thanks for advice. But yes I cleaned it and have set idle as you instucted. Ive done it probably 5-6 times making sure I get it right. I also pressurized the system and did find a couple of leaks but they were small and I fixed them. Did that about 4 months ago. Thanks
 
James M said:
You can't to my knowledge bypass the speed signal requirements in LH2.4, here is a good link on speedometer diagnosis, https://cleanflametrap.com/speedoDiag.html
Click to expand...

I didnt have time to diagnose the speed sensor but I did pull the speedo and tightened with connection as this link shows. Drove car last night, so far so good. Im still gonna go megasquirt. By the time you by the ostrich stuff and Eeprom burneer to do your own chip etc. You will almost be in deep enough to buy a megasquirt. Just some food for thoughts.
 
Do you know what pulse width your injectors are running at idle? With large injectors the idle pulse widths become very short and some injectors do not provide predictable fuel delivery at low pulse widths. Some brands of injectors claim to provide linear fuel delivery down to 1 millisecond; but, unless this is confirmed the reliable practise is to try and size the injectors for an idle PW of closer to 2 milliseconds. The other injector parameter that will affect idle is injector offset / opening time. I don't what an NLAO chip is; but, has it been coded with the correct offset for your injectors. Incorrect offset will severely screw up idle control.

Finally, are the injectors clean? Because of the short pulse widths dirty injectors can have a more significant effect on idle operation.
 
142 guy said:
Do you know what pulse width your injectors are running at idle? With large injectors the idle pulse widths become very short and some injectors do not provide predictable fuel delivery at low pulse widths. Some brands of injectors claim to provide linear fuel delivery down to 1 millisecond; but, unless this is confirmed the reliable practise is to try and size the injectors for an idle PW of closer to 2 milliseconds. The other injector parameter that will affect idle is injector offset / opening time. I don't what an NLAO chip is; but, has it been coded with the correct offset for your injectors. Incorrect offset will severely screw up idle control.

Finally, are the injectors clean? Because of the short pulse widths dirty injectors can have a more significant effect on idle operation.
Click to expand...

-I will see what I can find out. drove car around today, it died once. But still stumbles exspecially when I come up my dirve was which is up hill, then when I go to park it will stumble and try and die. I iwll contact both injector guy and the guy that made the chips. Thanks for the info.
 
I know this is probably a dead link but might help someone. I moved my 3inch amm to the cold side of intercooler. So far, no problems dying or stumbling. AFR readings are good. So I probably had AMM to close to turbo (had 45degree angle and about 5inches away) or had leak somewhere before turbo? I pulled my chips and they were marked for 3 inch amm. I do need a bigger turbo for my setup, I have 19t. Anwywways maybe this will help someone. I know the 3 inch AMM wont last long on 20lbs boost. But going MS soon.
 
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