tjbreen

My turbo is a stock K26/6. Nothing fancy.
I like the idea of bad grounds. My car has always had weird grounding issues.

Tom M'Guinn

Always good to check grounds.

I've learned time and time again that Vitesse's AFR is spot on if there is nothing else wrong with the car. I've had my share of compensating maps in the piggyback, and everyone of them ultimately turned out to be masking some other problem. Of course, you have to start with correctly matched parts. You mentioned 75lb injectors -- I didn't think Vitesse generally offered software for 75lb injectors? (72 and 83 are listed on vitesseracing.com for example...)

Thom

Good feedback, thanks.

tjbreen

I made sure that i ordered are the exact injectors the PO used from the same supplier. According to the supplier, these 75s are the replacements for the 72s and use the same part number (3145).

The MAF is currently grounded to the same terminal as an Ice Shark supplemental cable that runs to the engine block. Today I am ordering a complete grounding kit from Robby, the nice lister who has taken up where Ice Shark left off. This kit should eliminate any grounding issues I may have.

choinga

I did a supplemental as well from the front of the engine to the drivers side headlight chassis ground - I grounded my MAF down there...definitely improved things for me.

Where are you picking up +12v power for your MAF? I doubt an issue here would cause your particular problem and my experience is if you aren't getting solid 12v the car will run like crap (if at all).

Why wouldn't you order the injectors from John? I'm sure he could look up your chip and at least figure out what injectors you should have based on the map...dunno if he'd charge you for that...but it seems like the most logical thing to do.

tjbreen

choinga - I basically duplicated everything from the kit as it was installed by the PO. It is when things don't work that non-Vitesse parts are a problem. Believe me, I am up to speed on Vitesse support policy and will be ordering any future parts from them.

Thom

Hmmm... I have the battery cable kit from Robby with the cable between the side member and the hat for the upper balance shaft, but I suppose I will have to check again the ground for the MAF.

fast951

Guys, most times a ground issue will cause a rich condition. Of course, check the grounds and make sure they are fine, however don't ignore other possibilities.

tjbreen

I ran a bunch of tests last night based on posts by choinga and fbgh2o who were trying to solve overly rich issues with their installs.

My TPS and DME temp sensor tested OK through the harness. For the DME temp sensor, Clark's listed the warm (179 deg F) resistance for this sensor to range from 280 to 360 ohms and mine was right at 280, so I will replace it figuring it may be on the edge of acceptable. I may hook up a variable potentiometer to this lead to test the sensitivity of A/F ratio to changes in reported temperature. Clark indicated that the lower the reported resistance the leaner the mixture.

I ran a bunch of supplemental grounds and tested the resistance from a number of ground points back to the battery but did not find anything egregious but did note that while running, the voltage at the battery is 14.1 but the dash gauge is showing 13V. I may pull the insturment console to clean up the footballs but I have done this in the past to fix a bad temp and fuel level sensor with no success.

Full ground and positive kit should be here this weekend from Robby and I ordered a new fuel pump to replace the 23 year old one that tested ok but I wanted to eliminate fuel as an issue.

schip43

I know it would be a pain, but have you thought about returning the car to stock and then seeing where your at?

tjbreen

I could return it to the configuration it was in before but I do have data from the WB just before the MAF swap and was seeing 12.5 A/F ratios with the old Guru chips at 15PSI, so it has never been as rich as it should have been. I ran those chips for about 30 track days.

I did notice that the car runs hot when pushed hard on the track. I installed a 22x8 inch Setrab oil cooler up front to keep things within the comfortable range but, on warm days, I would get the light if the session was over 25 minutes long. At 11.5 it might have run all day without getting too hot.

VDubDoug1982

Did you ever resolve this lean issue? I'm having the same problem. 13s under boost.

tjbreen

I did. It was a while ago but my memory is that when I switched to a larger turbo and the AF ratios improved. I have been tracking the car for the last 10 years and I am on my second larger than stock turbo since 2010. AF ratios are in the low 12s high 11s under full throttle. I am on my second AF gauge and still showing 14.7 at idle. Something in my system didn't like a worn out K26/6 turbo. Car dyno'd a few years ago at 300+ RWHP at 15LBS boost.