VPC and a faulty TPS

[mr D]

Well i have a few problems. I am new to this forum but certanly not a rookie
Have a 97 Ecipse with a 6 bolt swap and the whole engine was rebuild. There is a Garret GT10 ( hybrid ) and lots of HKS stuff etc. It produces 400+ whp ( or at least it should when everything is setup right. )
Have FWD but the Quaife diff helps wonderfully and i love the machine. You can check it out here.

http://www.cardomain.com/memberpage/486477

Now that the introduction is done i want to ask if someone had the same problems as i have.
First my engine build. I have 550 cc injectors with the HKS VPC. The VPC has a car and injector specific chip. That chip can be bought with a max setting of 550. Is this correct or does anybody know if there is a 660 chip. I think my injectors are too small. Or can i buy the 660 injectors and install them with the 550 chip. I have a VPC so can correct any fuel differences. Will the setup work this way too or can the chip not be fooled.


When i rev the engine up it jutters very fast. It cant make any power when it does that but my wideband tell me it is not lean ( 10,8 ) so that puzzles me. But that only happens when i activate the boost controller. When it is off and i run stock boost ( 0.76 bar ) ther eis no problem and the engine revs like a sunshine all the way up to the limiter. But turning the Apexi on ( AVCR ) and setting it only at .8 makes it brrrrrrrrrrr.

Could it be that the settings are not right an the boost controller. What does the duty cycle do ? I have read the instructions but am not getting any wiser ( i am dumb )

That Brrrrrrrr makes me wonder if the injectors arent too small. But turning it only at .8 ???

Than the TPS. On the VPC i can see the TPS from 0 to 100%. When the engine is hot it stalls at 0%. Than when i stop the car and keep the gas pedal down it starts to climp up from 0 to 1 than 2 than 3 ???? what the.... is that. I have changed the wiring to the TPS and checked the connections. Even removed the wiring and soldered the three cables directly the the sensor but without any luck. It seems be be less faulty but still it has to be 100% ok otherwise tunig will be impossible.

Lots and lots of questions but i would be very happy if only one gets awnsered right. I hope someone can help me out here.
Thank you

 

[Maglin]

I think you have a problem with your AVC-R. Do you have a manual boost controler? Give that a try and see how it runs. I'm not to sure what scramble boost is but I know the AVC-R has it. If it is on maybe it is alternating from one setting to the next to help with traction. I've heard a lot of people have more problems than success with the AVC-R. It looks like a great controler but very PITA to set up. If an electronic Boost controler is your thing the prolific-B (Sp) is very solid. That is if the AVC-R is the actual problem. Does it also plug into your TPS?? If so then I think it could also be causing your strange TPS problem. Could be you just have a bad TPS...

 

[mr D]

Interesting conclusion. I did see it happen with the AVC R on. But when i got a little down i turned the thing off and it still did the % build up with full throttle down. But the wiring of the unit is seperate from any settings on the AVC R ofcourse.

I choose the Apexi because of its gear specific boost since i have a fwd.
Scramble boost is for a short burst of extra boost t the traffic light. I dont use that the engine is running very powerful without this feature. It is the dutycycle that puzzles me. I will check the apexi site now.

Thank you so far.
D

 

[ken inn]

first off, how the heck do you see tps on the vpc? i'm damned it any settings can be seen on vpc, there are only knobs.
i have 660's with vpc, but i have modified chips, both the 550 in the vpc, and a keydiver(search) chip for my ecu and 660's. works fine.
i suspect this anomaly is your vpc settings, most likely gain. gain needs to be set about 9 o'clock, and then make a couple of runs, especially part throttle, on boost. if it still flutters, back it off a couple of clicks. if it does not, give it a bit more till it does, then back it off. also, your response needs to be way on the plus side, at least 3 o'clock, maybe even more. make sure your map sensor is mounted higher than the throttle body, and the vacuum/boost line to it is the ONLY line, do not tee it with another line. the vacuum/boost line should be as big inside diameter as possible, and several of us have removed the inline filter, it is a restriction. vpc likes to run rich on low and mid fuel, so if you are trying to lean it out at mid fuel, try going rich instead, and see how that works. i have a 1g, and both low and mid fuel likes to be very near, or at 81. when tuned correctly, vpc is awesome. the response is way better, and this sucker pulls way better and harder than the 264 cams did. you might want to read up on the yahoo group, hksvpctuning. there are hardly any posts there anymore, but there is some very good information.
lastly, i have no idea on the effect of avc-r with vpc. vpc does alter timing, and it is possible avc-r is altering it so that ecu is confused. i think you should remove it, tune in vpc, then install other devices and retune. all i have with mine is an afc to fine tune, i think all you really need is a bit more fuel control.

 

[talon_boy69]

you should sheck for continuity(or however it is wtritten ) on the TPS cable of the VPC ( the one on the VPC harness between ECU and ECU harness).

 

[mr D]

flutters that sound like what it does on higher boost. Your story about the VPC sounds like the same thing that happens in my car. It runs indeed very rich. And trying to lean it with the AFC has little effect. Turning the VPC knobs to 9 oclock. Is that possible. I thought to 6 was max. So i was wrong. I have the gain on 3 now and it could be a little more. the second knob is for the total rich / lean setting. The fluttering could be caused by that knob then ? But with the same boost and the AVC R on it flutters. With the unit of ( same boost ) it doesnt. ? . I can check my TPS on the AFC. The values get strange when the engine gets really hot ( and you all should know how hot that is ) It did it again yesterday with with the boostcontroller off so i think the sensor is not right. I am probably best of repalcing that.

I did reroute so battery cables before the problem so the battery was dead for a few hours. Could any setting on the boostcontroller be reset so when i turn it on it has wrong engine values. The problem is that i havent build the engine and the electronics myself. I will check the vaccuum lines. But i dont think the problem wil be found there.
Again thanks for the additional info. I will check the VPC tuners site.
D

 

[mr D]

i have 660's with vpc, but i have modified chips, both the 550 in the vpc, and a keydiver(search) chip for my ecu and 660's. works fine.


My English is not one 100% but did you mod the 550 chip for the 660 injectors or did you just use the 550 chip with 660 injectors.

 

[ken inn]

my vpc came with the stock 450 chip, and a 660 chip. i got a 550 chip for the vpc from keydiver, and a 660 chip for my ecu that he designed to work with the vpc.
your settings on the vpc are whacked out. if you put all the knobs in the straight up position, this is what i would call the 12 o'clock position. if you turn the knobs clockwise, it is in the plus(+) side, and counterclockwise is the minus(-) side. the knobs, from left to right, should be response, gain, idle, and op out. the first knob, response, turn CLOCKWISE to at least the 3 o'clock position. this is tip in, like an accelerator pump jet in a carb. it adds fuel when you step on the gas. i have mine set on 5 o'clock.
the second knob, gain, turn COUNTERCLOCKWISE back to about 9 o'clock. this is fuel enrichment. it seems to have a big effect on part throttle boost. if you are getting this "fluttering" or fuel cut-like symptoms, turn it a couple clicks COUNTERCLOCKWISE. i have mine set on 8 o'clock.
the third knob is idle, this ONLY affects idle, below 1300 rpm. it adds or subtracts fuel at idle. you should have this set at the NEGATIVE side, mine is at 10 o'clock. the last knob, op out, is only for use with the gcc/f-con, and allows a finer adjustment of fuel trims, but the afc works better for this.
vpc is an awesome unit. in the words of a very well known and respected tuner who frequently posts on this group, "the vpc makes a lot of stand alone owners take notice".

 

[1LE]

It's really hard to beat the VPC for WOT performance. Response is always an issue, especially with 2g's. VPC like to be rich at idle too.