Help to solve my last few v8 engine woes ECU and tuning advice required.

[92 VP SS]

Hi all over the past 2months I've been trying to resolve and tune the running of my Automatic VP SS.
The original problem was the vehicle was getting consistant poor milage irrespective of driving style. 50k per 10L fuel.

Ive managed to get that down to about 65K per 10L, by general tuning, oxygen sensor, spark plugs, fuel filter, oil change/filter, TV cable adjustment, fuel dampener, driving technique.

The last 2 issues that are really bugging me are when coasting my AFR indicates 750 millivolts and that is the same reading as at idle when the engine is warm. It just seems to be such a waste of fuel. When coasting it will go to idle rich but if I lightly touch the throttle to the point that it doesnt accellerate it will drop to very lean 50 millivolts.

Basically now I think the key to regaining factory economy figures is sussing out the rich coasting and reducing the idle AFRs.

The last things I can think of is a problem with the map sensors or a leaky injector or something mechanical that is stopping the engine going into a lean no load coast.

I would really appreciated some constructive advice on how to solve these problems ??
Or does someone have some information I can study on how the ecu system works ?

Once I solve these 2 issues, that are probably related, I can just enjoy driving my car knowing that Im in control of my fuel bills. Ive read the ECU will take any opportunity it can to increase economy but it seems mine is doing the opposite when its not in closed loop mode.

Also my car is a NZ VP SS so factory its not fitted with cat and a sticker to that effect is on the strut tower. I know that if a cat is fitted the ecu will add fuel at times to help the cat but surely mine dosen't require that.

Kind Rgds

VP SS

[Circlotron]

Just google Delco 808.

You'd have more luck asking what foolly sick wheels look best on your car. Q.E.D.

[esponja_verde]

Does the torque converter lock up within a few minutes of the car being started from cold?

[92 VP SS]

Hi yes the torque converter will lock up within a few minutes from cold once I get to 90 Km. It seems to operate normally etc. It only takes me about 2mins of driving before it will lock up once I hit the motorway. Are you thinking coolant temp sensor ??

[92 VP SS]

Ive just discovered when my cars speedo reads 110 and I release the throttle I get fuel cut and afr goes lean, but if I do it at 100 i get rich idle 750 Millivolts. There must be something programmed into the ecu that cuts fuel on deaccell from 110 and over.. I really want mine to occure across the speed range ? It must be a programming thing so I will need to talk to a programmer for some advice.

[92 VP SS]

Well it looks like Ive solved my issues, I think its a programming issue on the performance memcal I have. It has different fuel cut paremeters from the standard VP SS Memcal. I swapped my memcal back to the standard and it fuel cuts more frequently and at lower speeds also it doesnt idle so rich and idles in closed loop more often. When Im coasting at about 50 or 60 k rather than it going to rich and staying there it flips to closed loop as well. So it appears its a tuning issue and I think my best option will be to run the standard chip and increase the base timing from 10 to 12-14 degrees btdc.

The other thing I noticed with my standard chip in OD the TCC locks at just over 80k where as with my performance chip TCC locks later at about 90k.

Anyway I think the factory has better settings and to get a bit more pep i will adjust base timing :-)

So problems solved car is running great and doing the right things to save me $ when cruising doing chores.

[Circlotron]

The other thing I noticed with my standard chip in OD the TCC locks at just over 00k where as with my performance chip TCC locks later at about 90k.

My TC locks at 70 kph and unlocks at 64 kph according to the data I pulled out of the eprom. It has some custom gas ignition table in it as well so the TC figures may not be standard but they seem to work well enough.

[Munz]

greenfoam that rig

[commoVT]

your wasting your money man!!! save up and get a v6

[92 VP SS]

Haha, commoVT, I can offer you the converse in advice Im more of a V8 man . My 8 is going very well and economy is great its like a tap that you control how much it opens, I was just annoyed at it dumping fuel when coasting, seemed dumb to me but it was a tuning issue, I shouldn't of messed round buying tunes without doing my research . Next tune I get cant be a magic tune and I will want to know what changes have been made and what it was based off.

Yeah munz I heard G foam is really good and have read a-lot of his forums it sounds like he's got his head screwed on well. Shame he's not posting alot these days.

[stuntmanmike]

My 2 cents:
Is the fuel pressure regulator okay?
My fuel economy sucked big time in my V6 and traced it down to being a faulty FPR unit. The tell tale was that the balance line to the TB was wet with fuel when it shouldn't be. Best of luck.
PS. Greenfoam is a legend and top bloke!

[92 VP SS]

Hi Stuntmanmike, yeah the fuel regulator is fine no leaks into the vacuum tube, I do want to get it a pressure gauge tho to verify its PSI. Believe it or not I got some good results economy wise when I installed a fuel dampner ! as my SS didnt have one.

Do you know why Greenfoam stopped posting on the forum, maybe its because he mastered the commodore ?