Sluggish after JDM tune
10-03-2014, 09:10 AM
#22
[QUOTE="Blown Ford;3736289"]
I definitely agree that its in the tune since I'm having the same exact issue..
So I found a document that says the roush kit comes with 38# injectors, I put 39# on my tune sheet. The only numbers on the injectors don't pull up anything. Would thus cause my issue? /QUOTE] That's odd. The Roush kits came with 42lb injectors. They were green and made by Bosch. Never heard of the 38lb. Fords injectors are 19, 24, 30, 39, 42, 47, 60 and so on. The 39lb injectors are blue and often reffered to as Cobra injectors as they were produced for the 03-04 Cobra. As for the throttle plate. You can use the SCT data log and should see throttle postion at 100-110%. The easiest sure fire way to know is to disconnect your intake from the throttle body, turn the key to on but don't start the truck, have someone press the gas to the floor while you watch the throttle plate. I think your issue is in the tune. However it never hurts to check everything else.
10-03-2014, 03:30 PM
#24
Member
Thread Starter
Problem solved!
JDM sent me these instructions this morning. Apparently they didn't realize I had an older kit. It was installed in 2006, and they stopped using the boost solenoid in 2008 I guess. Jim is still working on my cold start issue.
Last edited by '06Roush_150; 10-03-2014 at 03:59 PM.
10-03-2014, 05:05 PM
#26
12 Second Truck
Yes I've seen them listed at a few places for sale rated at 38lb/hr. However the description from Roush says 5 grams per second. Regardless the flow rate is affected by the fuel rail pressure. The injectors are said to flow xx lb/hr at xx psi or bar. Running those injectors at 43.5 psi fuel pressure will make them flow around 42lb/hr. Eitherway I don't think you did wrong in your description to JDM. However you may want to call them and discuss the exact injectors you have per the part number. Scaling and tunning values are provided for injectors. And if they set yours up based on 39lb Cobra Ford Motorsports injectors there may be an issue verses setting up the tune based on the injectors you actually have. It's worth a follow up call.
10-03-2014, 05:06 PM
#27
12 Second Truck
Correct. That solenoid can limit boost to 6psi if I'm not mistaken.
10-03-2014, 05:15 PM
#28
Member
Thread Starter
Correct. That solenoid can limit boost to 6psi if I'm not mistaken.
10-03-2014, 10:52 PM
#29
How old is your battery?
I'm doing some more thinking here and I'm wondering if injector latency might be the biggest contributor cold start issue..
Injector latency is a certain constant of injector pulsewidth added to the calculated pulsewidth to compensate for the time delay in opening and closing of the injectors. Larger injectors open and close at a slower rate so this constant needs to be increased appropriately.... Its biggest affect is on the idle, too high and the car will idle rich or not run at all; too lean and the idle will be lean or not run at all...
My battery is at least 4 years old, but I suppose it's possible for an old battery to be the cause. The injectors actually function directly off the battery during cold starts.
I'm doing some more thinking here and I'm wondering if injector latency might be the biggest contributor cold start issue..
Injector latency is a certain constant of injector pulsewidth added to the calculated pulsewidth to compensate for the time delay in opening and closing of the injectors. Larger injectors open and close at a slower rate so this constant needs to be increased appropriately.... Its biggest affect is on the idle, too high and the car will idle rich or not run at all; too lean and the idle will be lean or not run at all...
My battery is at least 4 years old, but I suppose it's possible for an old battery to be the cause. The injectors actually function directly off the battery during cold starts.
10-03-2014, 11:57 PM
#30
Member
Thread Starter
How old is your battery?
I'm doing some more thinking here and I'm wondering if injector latency might be the biggest contributor cold start issue..
Injector latency is a certain constant of injector pulsewidth added to the calculated pulsewidth to compensate for the time delay in opening and closing of the injectors. Larger injectors open and close at a slower rate so this constant needs to be increased appropriately.... Its biggest affect is on the idle, too high and the car will idle rich or not run at all; too lean and the idle will be lean or not run at all...
My battery is at least 4 years old, but I suppose it's possible for an old battery to be the cause. The injectors actually function directly off the battery during cold starts.
I'm doing some more thinking here and I'm wondering if injector latency might be the biggest contributor cold start issue..
Injector latency is a certain constant of injector pulsewidth added to the calculated pulsewidth to compensate for the time delay in opening and closing of the injectors. Larger injectors open and close at a slower rate so this constant needs to be increased appropriately.... Its biggest affect is on the idle, too high and the car will idle rich or not run at all; too lean and the idle will be lean or not run at all...
My battery is at least 4 years old, but I suppose it's possible for an old battery to be the cause. The injectors actually function directly off the battery during cold starts.