This is my first time posting in this section of the forum so please bear with me. I am having an issue with a startup-stall issue on my truck. On a dead cold start the truck has no issue starting. Sometimes after driving a short while and then stopping, upon restart the truck will turn over, catch and then the RPMS will drop past the idle (800 RPM or so) and then drop lower and eventually die. Starting around frame 1650 of the attached log you will see what I am talking about. This occurred this morning where outside temps were around 40*F and coolant temp was around 160*F. After numerous restarts, it finally worked and the truck ran fine. I use Justin from BlackBear for all my tuning through the AutoCal. I know he locks his tunes so I cannot say what the settings are. This has been going on for a while and I have probably sent Justin a dozen or so logs and he in return has sent back just as many "modified" tunes to try and rectify the problem. Nothing seems to be helping.

The only other issue I am seeing is on occasion on a dead cold start if I try and put the truck in Drive or Reverse too soon, the RPMS will drop and fluctuate severely and sometimes it will catch and idle fine or sometimes die.

Modifications are in my signature. I'm just looking for some second opinions because it is beginning to get frustrating. Thanks in advance.

 

I don't know if this will help but I went out this afternoon and started the truck and let it run for a bit. I then shut it off for a few minutes and the tried starting it up. It did the same thing; reved to 1200 RPM or so and then stalled. I decided to unplug the MAF and try starting again and when I did the truck came down and idled fine. Could this mean my MAF is going out? Could it mean the MAF tables need correcting?

 

It sure sounds like the idle airflow tables to me.

 

By unplugging the MAF and getting better results would seem to indicate a miss match in airflow measurement between the MAF/MAP. Both tables probably need to be calibrated. Your tuner is going to need A/F data for this. Warmed up, fuel trims on he can deduce this via the autocal. You need to add fuel trim data to your logfiles and send it to him.

 

I spoke with Justin yesterday via email in response to my latest log I sent him. Because this is happening at startup during certain situations only there is not a lot of data for him to go by. What he is seeing though is negative fuel trims when it actually does start and keeps running.

I explained to him that this all started after the installation of a 1/2" phenolic spacer between upper and lower intake of the Magnacharger. My question to him was if the added plenum volume (doubled in size) could be causing this issue?

He has yet to respond.

 

I don't see the volume of the plenum being a problem. The bottom half of the plenum has O-rings that keep it sealed. Did the top half of the spacer require O-rings? It also needs to be sealed around the bolts that hold it to the head, not just the bolts that hold the halves together. Negative trims should not indicate a leak, but I can't think what else could cause this.

 

The kit comes with new orings for both sides along with enough oring material to cover the entire plate (both sides). I also sealed it with some RTV so i doubt its leaking. Negative trims also do not point to this.