Okay to make a long story short, I've been having an cold start issue for like two years now. Sometimes it's intermittent, and on occassion it wouldn't do it. since it wouldn't do it until the car sat for awhile it was hard to check things. I've replaced and swapped all kinds of things with no avail.

After looking through a lot of my logs I see the problem was occuring after I swapped to the 30# SVO injectors.


So I'm wondering if anyone who has done tuning for new injectors or has a tune from Madz28, or PCMFORLESS, etc could tell me what they have for values (Bryan did the original tune for my 30#s) for Injector Offset Vs Battery Voltage Table, and the Low Pulse Width Injector Offset Adder vs BPW table. If you don't want to post numbers I've included my tune, and you could PM me.

Thanks

Matt

 

Post a video recording how it starts. Have you ruled out the fuel pressure regulator?

 

what format is that tune in?

 

bin format. for Cats Tuner.

Video isn't going to tell you anything really. It wants to almost die, but goes away as it warms up. Stock 165K FP was 2 psi out of spec without vacuum on, so it was replaced with AC Delco unit, and fuel pressure is not an issue. Doesn't Drop a lick while car is doing it. Fuel pump runs strong the entire time.

I have a log I can send to anyone. Can't upload it as it's 2mb.

Matt

 

i dont have tuner cat. but i will shoot you some IFR numbers for those injectors so you can compare.
but that dont sound like your issue.

 

Here I'll cross post information from my thread on ISSF.

What it wants to do is almost shut off. it idles down to almost 300 rpm, but it recovers and goes on it's way. Sometimes you can feel a stumble in the 1000-1200rpm range. Above that there is no stumble The weird thing is on occasssion it won't do it.

I've checked just about every sensor in the car. All of them are AC Delco and fairly new. They're been checked if they could. I've Checked grounds, and even tore apart a lot of the wire loom up front to check for a pinched or exposed/shorted wire. NOTHING at all. Opti passed test, and so did IAC. ICM and Coil have been replaced with different units, no change. Same with EGR. I checked compression last year, and all cylinders were within 5% in the 200-210 range I unplugged the MAF at one time and let it run in SD, and no change and it ran WORSE. Replaced the ECT no change.

Opti is about 2yrs old now. New vacuum harness was installed when it went in. (AC DELCO UNIT)

Now just the other day I finally noticed something with the addition of the vacuum gauge I added a little while ago. When you first start the car up, and you move the steering wheel back and forth, or put the brakes on, turn the AC on and off or put the car in any gear, I see the vacuum on the car dip 5-10" HG. In addition to it dipping, sometimes the idle will do as I described above, and sometimes not. I noticed vacuum at cold startup is in the 17" range also. When the car is fully warmed up Vacuum is around 21.5".

Once the car warms up, the most the vacuum will dip is 2" and that's turning the AC on and it quickly recovers. All vacuum lines are plugged in and not leaking.

replaced the IAC. Old one wasn't that dirty. sprayed the IAC area out with TB cleaner. Reset the IAC per instructions. Still no change in symptoms. It's actually kind of gotten worse this year.

PCV valve probably has less than 7,000 miles on it and is an AC Delco unit. PCV valve was replaced just the other day also.

Got the intake pulled today. Lifter valley as I expected was pretty damn clean. I took that little cover off the bottom of the intake, and man was there a lot of "GUNK" in there. I guess rather in there, then somewhere else. IT was the original 170K intake, that really was never cleaned when i did the gaskets the first time.

Glad the powdercoated intake was spotless clean.

Gaskets were in good shape, and so was silicone. New Printo Seals, and "THE RIGHT STUFF" went on.

No Change after new intake.

If someone wants me to send the log to them I can. you can see in the log when the idle dips the Map sensor reports a lot more air (10" HG more). You can see variations in the fuel banks in open loop also. That's what makes me think an issue with the injectors.

Like I said I'm running out of ideas what could cause this stupid issue. I hate just throwing parts at it, so that's why i made the post. I've swapped everything except the injectors, 02 sensors, or MR OPTI.

 

Send me your log in uni format and I'll look at it in DM tonight.

 

here's a zip with the tune and the datalog.

http://www.filesend.net/download.php?f=a5dfda6bd28530fe6444fc418ed14bab

 

I've had something similar with my car since I got it. When it starts cold and is in open loop, there's a really bad stumble and the car almost wants to die. As soon as it warms up and hits closed loop, it runs fine and smooths out.

What I think is going on is that there is a vacuum leak somewhere. In open loop when the car is cold it's running really lean, but the computer doesn't know it yet (since the O2 sensors aren't warmed up). The computer is following the tables for the fuel ratio, but they're off because it's not accounting for the vacuum leak. Once the car warms up, the computer sees the lean condition and maxes out the trim values to put more fuel in. This brings the AFR back to where it should be and the car runs smooth.

I don't know if this is the same problem you're having, but it sounds similar. In my case, I really need to track down where the vacuum leak is coming from and hopefully that should fix the issue.

 

I thought it was a vacuum leak, but I've checked and verified all vacuum hoses and none are leaking. Intake Manifold (powdercoated one ) was replaced to check gaskets.

Matt

 

well today was work day. 93 degrees in the sun working on the car. Waterpump came off (replaced with new unit) new opti seal, new WP seal, new crank seal. I took the old optispark off (had a new Delphi to put on anyays). Took it apart and it looks interesting:

Cap didn't look bad at all for 2yrs old:



Rotor had some dirty on the end, but still not bad:




Found this:!



And:





Interesting none of this "rust" is on the bottom of the optical disc. I dont know if I got a bad unit with rust in it already or what, as the vacuum harness was new, and I kept things off the opti, and the seals were so tight I had to pry the sucker apart.



needless to say car is running a lot better. Not sure 100% yet as I ripped one of the ends off my MSD wires taking it off. Luckily it was #3 so it won't be a PITA to replace, but I got the end back on there for now.