I have DSM 450cc injectors on my turbo d16z6 and the idle is a little lumpy like its misfiring. This happens when the car reaches operating temps. When I start the car COLD the car idles like a dream but when the coolant reaches around 180 deg the car idles lumpy and sometimes stalls out. The car was professionally tuned and goes like hell and makes 225 @11 lbs. I've done some research and some point towards the DSM injectors. I've tried a different IAC valve as I thought it was the culprit, no difference. Other things I've changed have been the 02 sensor, coolant temp sensor, new ELD as my car was throwing a code for ELD, changed it and still a lumpy idle. What do you think?

 

ya my **** does the same thing. bout to toss my dsm's when i get back home. how's your idle rpm + vacum?

 

Idle rpm is to spec and I'll check vacume this afternoon.
Thanks

 

It has to be in the tune. Plenty of people use them with no issues. Make sure you are not going lean once its at operating temp. Is it running closed loop?

 

Its operating @ stoich at idle or at least thats what my tuner has told me.

 

what are you tuning with?

 

Techtom. Japanese software used by allot of tuners over seas. Idle is @ 16.5 in/hg.

 

Its in the tune. Ive got 15+ cars to idle like stock with DSM 450's.

 

yup its in the tune. and your tuner saus stoic, so that means you are driving around without a wideband???

 

the truth.

wish there was more info on this techtom stuff. is it a stand alone? eprom type? piggyback?

 

I had dsms and it idled like stock

 

I have used dsm 450ccs aswell with no issues. Occasional slight faint idle pop, but the car was still running very smooth. I don't think there is any paticular reason you should have a bad idle with these injectors as old as they are.

What is poor with the idle? slight surge? popping? unstable?

 

No wideband. The car stumbles or misfires occasionally. Idle does not surge. Again this is only when the car is at operating temp. When I start the car cold the idle is solid as a rock @1500 rpm or so. The lumpy idle starts when the car is warmed up. Maybe its an IACV setting or battery offset voltage issue. I'm gonna go back to the tuner next week and see if we can get to the bottom of this. I thought I'd ask the community first to see what you all thought. The consensus is "its the tune".

Techtom is the eprom type software. Kinda like Crome or the other types.

 

my dsm's idel smooth @ 1k, 21" vac. but the afr's are not consistent.

for your iacv, the book says to get the car warmed up, then remove the iacv plug, set the speed to around 400rpm, plug it back in, clear the code, then adjust the engine speed to 750-800rpm at the throttle body screw.

 

Set the speed how? You mean RPM? Through tuning in the software or through the throttlebody screw?

 

Your problem is likely not your injectors. I have tuned more cars then I can remember on dsm 450cc injectors without idle issues.

 

get the engine to operating temp, disconnect the iacv, adjust the idle at the throttle body so it is around 400, then plug the iacv back in and adjust the rest on the computer...

I have done a few on 450s that idle great, although the AFR tend to fluctuate a bit at idle I have noticed...

 

Thanks. I will try this .

 

UPDATE!!!
Alright, I changed my injectors back to stock and disabled the chip in my ECU and still the cars idle stumbles occasionally so its NOT the tune or injectors. Now I'm really stumped. Maybe it has something to do with the FITV or IACV. My turbo is a GT series turbo so it has coolant lines which are inline with the FITV and the head. Maybe the heat of the coolant coming from the turbo is too extreme for the FITV or IACV causing them to not work well. I'm really raeching out now. Totally stumped.....