hot/humid weather - truck runs horrible!

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Garrett4.0
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Posts: 5
Joined: Mon Jan 16, 2006 8:42 am

hot/humid weather - truck runs horrible!

Post by Garrett4.0 »

4.0 SOHC
Stock EDIS
To4e turbo
MSII v3.0, v2.35 code, MT 2.25
LC-1 wideband
#30 high impedence injectors

Ive been playing with truck getting it tuned and everything. From a cold start the truck idles and runs perfect. Ive had it up to 4000rpm and its runs pretty good so far. Warm starts are a no go, ive played with the afterstart but cant seem to get it to catch. It will start and die with each key turn. Today its 92 degrees out with a humidity of 50%. My truck has been sitting in the garage so the coolent temp was 91 and and the MAT was in the 90's also. The truck started and died as usual. Normally I just feather the gas a bit just after cranking and it catches fine and stays running perfect. Well today I feathered the gas it started but runs horrible, its chugging and puffing white smoke like crazy. As soon as I take my foot off the gas it dies too. I noticed my PW's while cranking where 13-20ms. Is this typical for a engine to run like this with high temps and humidity. Just sitting in the truck i was sweating like crazy :|. Now tommorrow is supposed to be even worse so I'll take a datalog and post that with my msq. Does anybody have any ideas in the mean time? Thanks
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mops
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Post by mops »

yes, i got the same problem.

problem is that MS calculates air density based on MAT and ideal gas law. this works for most ppl, but doesnt really work for others - you and me are extreme cases affected by the issue.

ideal gas law basically overcorrects....

when mat reading is high MS is leaning out mixture, but it is leaning it too much, so at extreme cases it will cause hard or no starting at all, bad running idle, etc.

try disconnecting yout MAT and then it should read 21drg C flat, which should make the car start /run just fine... perhaps a bit to rich...

see whether that helps you.

I founf that my car does not need ASE when warm, but absolutely requires it when cold....
BMW, 1985, E30, 325i, 2-door, 5spd , 127k miles, short shift, MSII, V3/code 2.684/60-2 wheel/MT 2.25, LC-1 wbO2, ignitor module mod driving msd coil/, 3 pin Bosch PWC IAC mod
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MegaScott
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Post by MegaScott »

Are you running with baro correction enabled?
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mops
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Post by mops »

i dont think it's a baro correction issue... but I think i run no correction....
BMW, 1985, E30, 325i, 2-door, 5spd , 127k miles, short shift, MSII, V3/code 2.684/60-2 wheel/MT 2.25, LC-1 wbO2, ignitor module mod driving msd coil/, 3 pin Bosch PWC IAC mod
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Garrett4.0
MegaSquirt Newbie
Posts: 5
Joined: Mon Jan 16, 2006 8:42 am

Post by Garrett4.0 »

Well I guess the hot weather just got to my head. I forgot to plug my line in for the map sensor. It still starts and runs for a sec or two when warm. I played with the afterstart but it doesnt seem to do the trick. I did however get it to start when i opened up my pwm valve a bit more. It was set at 50, so I dropped it to 40 and it started. But it idles too high so I had to put it back to 50. Is there a solution for this? Thanks
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mops
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Post by mops »

i'm not sure about ms'n's, but in ms2 cranking idle valve position is adjustable separately from running idle valve position...
BMW, 1985, E30, 325i, 2-door, 5spd , 127k miles, short shift, MSII, V3/code 2.684/60-2 wheel/MT 2.25, LC-1 wbO2, ignitor module mod driving msd coil/, 3 pin Bosch PWC IAC mod
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Garrett4.0
MegaSquirt Newbie
Posts: 5
Joined: Mon Jan 16, 2006 8:42 am

Post by Garrett4.0 »

This is straight from the manual:

# Select the 'PWM Warmup' option for the algorithm under 'Idle Control' in MegaTune.

# Note that the 'Start Value' and 'Time Based Afterstart' parameters in the same dialog do not apply to PWM use (the PWM% is dependent only on the coolant temperature)

I just left the 'Start Value' and 'Time Based Afterstart' fields blank because they dont apply according to the manual. Now those are filled in and the truck starts great when its warm. Thanks mops
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mops
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Posts: 217
Joined: Sun Sep 25, 2005 4:13 pm
Location: Auckland, NZ
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Post by mops »

Garrett4.0 wrote:This is straight from the manual:

# Select the 'PWM Warmup' option for the algorithm under 'Idle Control' in MegaTune.

# Note that the 'Start Value' and 'Time Based Afterstart' parameters in the same dialog do not apply to PWM use (the PWM% is dependent only on the coolant temperature)

I just left the 'Start Value' and 'Time Based Afterstart' fields blank because they dont apply according to the manual. Now those are filled in and the truck starts great when its warm. Thanks mops
I actually noticed that 'start value' does work durning cranking... at least at datalogs....
BMW, 1985, E30, 325i, 2-door, 5spd , 127k miles, short shift, MSII, V3/code 2.684/60-2 wheel/MT 2.25, LC-1 wbO2, ignitor module mod driving msd coil/, 3 pin Bosch PWC IAC mod
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