this doesnt seem like a major problem but i want to prevent a bigger problem from happening if need be. i drive a 03 5spd and when im going about 40 mph and take the car out of gear into neutral and coast, the RPM's drop and "bounce" at around 400RPM and then the engine stalls while coasting. i troubleshooted it and drove into 5th gear going about 55mph and put it in neutral. same thing happened, the car stalled. when im going 30mph and under and throw it in neutral the RPM's drop, bounce a little, and then level off to the normal idle RPM and the car doesnt stall. any idea whats happening here?..i should be able to coast in neutral at what ever speed i want right and the RPM's should just go to idle? the car is a manual so this seems very odd that this is happening. I DO have aftermarket parts (hopefully these arent causing the problem). SRT intake w/ race ECU piggyback, toyomoto headers, y-pipe, HKS dragger exhaust..if any1 hs any info ide really appreciate it. other than that the car idles perfect and consistent at a dead stop and the car operates fine while driving normaly.

 

any help with this?

 

Your best bet would be asking on the MY.IS forum

 

I think I know what your problem is.
First did you take out the piece of metal that covers the hole in the SRT intake heatshield?
If not, did you angle the MAF to face the engine?

 

yea i even have a air scoop on the headshield...talked to JM Lexus about the problem and one of the techs said it may be getting too much air when its coasting because the rpm's are low and it doesnt need as much air as its getting which is throwing off the a/f ratio and effectively stalling the engine..does this make sense?

this is my intake setup:

 

not exactly.. what tube is that??

 

Ok now do this;
You know where the MAF is plugged into the SRT is a separate tube from the rest of the system. Loosen that tube and rotate it clockwise till the MAF sampling tube inside the pipe sits perpendicular to the ground. The MAF wiring harness from the car will look to be plugged in from the bottom in that position, and the outside portion of the MAF will face the engine block.
Reset your ecu (negative battery terminal off for 10-15mins, step on brake pedal for 10-15secs after battery terminal off). That should solve your issues.

 

thanks a bunch kponti, ill try this tonight and let you know if the problem resolves or not. thanks again!

 

I'm having the same problem only mine is an Auto. I'll prolly try this when I get home too

 

yea.. rotate the MAF sensor tube facing towards u and down....... not up.. it will cause stumbles in idles and acceleration. The sensor is not reading right, because the MAF sensor is not in it's certain degree angle position.

 

wow...for a second i didnt think this would solve the problem but it TOTALLY did!..my car actually runs so much smoother and feels stronger!..no more stalls! and no more stumbling idles!..awesome! thanks so much for your help everyone.
-kyle

 

hell ya!! im glad it worked out for ya!!!