Cold start issues

[Rob05GT]

Hey gents:
Here is the issue I've been having ever since my supercharger install.
If the temp is below 40 degrees or so. The car is very hard to start. Usually very very rich.
Cold drive away is usually very, stuttery, that is the only word I can describe it, almost as if it is pulling timing like crazy.The car has been re-tuned many times to try to correct this. It is better than it used to be but still not great. Once it is warmed up it runs absolutely awesome.
Has anyone ever experienced anything like this before?
It is driving me mad and I'm almost ready to rip out the blower and go back to stock as this has been going on for almost a year.. The car is an 05 auto. Roush TVS supercharger if that helps. If more info is needed let me know.


Thanks
EL storcho

[Blackmare]

I had similar issues with my previous supercharger setup. Cold start was fine, but cold drive away it would buck and stutter like it would lose power and then catch itself. In the end, a new tune using Cobra 39# injectors solved the issue for me. Previous injectors were some no name 45#'s.

[ZR]

+1 on the above
Difference in Scott's car with correct injectors + retune was night and day.

[Rob05GT]

Who did the re-tune if I may ask? I have what I'm assuming are Ford 47# injectors. Was part of the kit.

[Blackmare]

Diago did my tune. I'd talk to a tuner, find out if you can use more popular injectors. The issue I had was trying to tune around the 45's and it just wouldn't work. After the 39's and re tune, it drove like stock.

[ZR]

Kit shows as coming with 52 lb injectors. Possible your tuner did not dial in the correct ones? Well worth checking further before chasing the issue further.

[ZR]

What plugs and at what gap are you running?

[Rob05GT]

HT0's and .28 gap If I remember correctly.
I'm almost sure that they are Ford Racing 47# injectors.

[ZR]

Similar misinformation when I installed Scott's Whipple. Instructions called it one size while online spec said another.

[ZR]

Assume new intake gaskets?

With the correct parts and correct tuning, should have stock type drive-ability.

[Rob05GT]

Just called Roush themselves and they confirmed that they should be 52# injectors.
Have to call the shop that did the install to see what they put in.
Don't have the car handy to see what they are. Tranny just let go as well.3rd gear went bye bye. Been a great week.

[ZR]

That is a shitty deal on the trans.
Be interested to hear which they tuned for.

[ZR]

We ended up basing em off the actual part number printed on the injectors themselves.
JT has a close up with numbers in this ad for his used ones.
http://www.torontomustangclub.ca/forums/showthread.php?1108-FS-USED-GT500-Injectors-x-8

[Rob05GT]

I know that's why I'm on a mission to figure this out.
We did a smoke/leak test to see if there were any leaks and there were none.

Does this make any sense to anyone? I found this while trolling another site(All ford mustangs.com)
Another guy had a similar problem and this is an smidge of what he found to be the problem. the whole post is actually a huge read.

"So when idling, the throttle blades are almost totally closed. There is little vacuum in the intake tube, but on the other side of the throttle body, there is 20 inches of vacuum. When you give it gas, the throttle blades open and suddenly you have vacuum in the intake tube, but vacuum drops on the other side of the throttle body (and in the manifold). So the PCV side is not sucking as much air from the crank case, but there is now vacuum in the intake tube. The passenger side crank case vent should have a valve to keep from having the higher pressure in the crank case from venting air back to the intake tube, which has low pressure when you first give it gas. Once the pressure equalizes, the PCV side is pulling air out of the crank case, and the vent side is letting air go in. However, if the valve is bad in the passenger side, it will act like a vacuum leak for a short time, causing the lean condition, and causing it to bog. When cold, the blow by is much worse, and much more air can come in, allowing it to really lean out and bog until the pressure stabilizes enough to no longer be a vacuum leak, which is when it finally takes off.

So with an "intermittent vacuum leak" like this, the short term fuel trims and long term fuel trims were all over the place, causing just poor running in closed loop mode. When going wide open throttle, the trims are ignored and the maf table is all it pays attention to, and it ran great.

All in all, the problem ended up being a bad vent valve in the valve cover - surely a result of baking the powdercoat on the valve cover. I closed off the 3/8 fitting on the intake tube and attached a basic crank case vent filter to the valve cover, and the problem is GONE. Fuel trims are always near zero now, the bogging is gone, and even cold it runs like it should. I am back to the standard Kenne Bell tune and all is well."

Any thoughts on this one?

Thanks for the input .
If it works out beer may have to be on me.

Rob

[ZR]

Easy to test, block off the pcv hose.
Assume no open breather on the V/C?

[Rob05GT]

Tuner thinks that they were the 52# ones. Won't know until I can pull one to check part #'s.
Car is in the shop for the transmission and new driveshaft right now.
Going with a Performance Auto 5r55s with Hardened input shaft, and a one piece driveshaft.

[ZR]

Please let us know how you make out.

[Rob05GT]

MAF transfer function was calibrated in real time. Just talked to the tuner.

[Rob05GT]

Revisting this thread, I'm about to get the car back finally from the trans shop. They took it for a road test and confirmed everything is working great. I asked them how it cold started and they did confirm that until it is warm it is finicky. I talked to the shop where the install was done, in Michigan, and I think they are done with it. I got the reply that if you get codes e-mail me other wise it just needs to relearn the drive cycle. Give it about 8 to 10 good drive cycles and you should have no more problems. I'm seriously thinking of just cutting them loose and starting from scratch.
Now, what are your recommendations for tuners here in Ontario?
I know of Diago, Dasilva's, Pat from steeda, Miseners, who has experience with them?
I know they are all good at their craft.
I would like to get this solved once and for all.


Thanks for the input.

El Storcho

[ZR]

All of the ones you've listed are an excellent choice. I'd makes some calls n figure out who best suits your needs they discuss the combination they like to tune around. Suspect at least some will suggest dropping back to the 39lb Cobra injectors.

[Rob05GT]

Finally got the car back from the shop, everything seems to be in order. trans shifts smoothly, no vibration from the drive shaft, Put about 250kms on the car, passed the e-test with the evap system not ready but that is okay. Came out of the MTO, car was still warm, threw a P-0174 too lean bank 2 code. Thankfully it did it after the e-test, ccould this be from a loose O2?
Thanks

[Rob05GT]

Went under the car, everything was in order. Cleared the codes going to see if it throws more. Driveshaft looks like a good solid piece.

[Rob05GT]

Revising an old thread.
I finally had the car retuned from scratch. Couldn't be happier, the car is very driveable. seems like the original tune was very suspect.
Thanks to all those involved, for steering me in the right direction. Now I can actually drive the car and not worry about it.

Rob

[ZR]

Awesome news, hope your enjoying it.

[Stephen06GT]

Awesome news, hope your enjoying it.

X2. Congrats!

[ZR]

Almost forgot, thanks for the last post. Always cool to hear how things work out in the end.

[Uncle Buck]

Glad to hear the car is dialled in. I'm hijacking a bit on the injector info. I'm a little confused about the whole rating thing. I understand that GT500 injectors are the 52lb Bosch injectors yet I hear them referred to as 47's. The difference being fuel pressure. I read at 43.5 lbs of fuel pressure they are 52 lbs, more at higher pressure and less at lower pressure. At the typical mustang system pressure they are 47. Sound right? If it is, what do you tell your tuner, 47 or 52

[Rob05GT]

The injectors that were supplied with the kit were the Delphi 52# injectors. I always monitor my fuel psi and it sits right between 40 to 43.5 psi. I told him that they were the 52# ones he said most guys use the 60's but he was happy with them. I did not run out of fuel on the top end on the dyno so they were plenty big enough.
Hope this helps.

On another note I still have to cold start/drive the car, but I'm confident that it should be A-Okay. will keep everyone updated.

Rob