VT Not Running Right :S

[holden_4aw_lyfe]

hey guys,

i have a vt 97 series 1 commodore, and spent a good ammount of money on it for mods as you can see on my "My Ride" thread. i took it to a dyno day and put it on the dyno, and the end result was worse than what i would have got if i put it on stock...ive gone backwards :S. The dyno results were wayyy too lean, and another person said theres a flat spot in my motor...just wondering is there any suggestions on how i go unleashing the full potential of this car? because it has so much more, but i dont know what to do any more...

cheers

[SMOTAN]

Have you got a copy of the dyno sheet you can post up for us so we can have a look?

Also what types of modifications have you done? Exposed pod filter could do less for the car but couldnt cause as much havoc as you have explained.

[holden_4aw_lyfe]

Heres the dyno, and mods...


Engine:

- Pacemaker Blue StreetPRO Extractors
- 2.5 inch Custom Exhaust With Dual Exhaust Chrome Tip
- Mace Engineering Custom Cold Air Intake
- Mace Engineering Custom Plenum Spacer 17mm
- Mace Engineering Custom Cold Air Inlet Manifold Spacer 25mm
- Mace Engineering Custom Bored Out And Polished Throttle Body 69mm
- Custom ECU Chip
- SAAS Air Filter

[billy bob]

when you say custom chip is that mail order or on a dyno

[edals]

How Many KMs on the VT mate? And the Custom ECU Chip as bob said.

[holden_4aw_lyfe]

the car has done 230,000kms just hit, and the chip is a custom mace engineering mail order chip...i was thinking, would bigger injectors do the trick? because to me on that dyno looks like its running amazingly too lean because the injectors cant keep up with the fuel that needs to be injected into the motor??? just a thought?

[doyab]

on thats dyno sheets seems to me the power flat lines when the afr suddenly raises? but idk.

[Tsunamix]

To my vaguely knowledgeable in a broad sense eye, the AFR is way to lean and high eand low end. SOmething like 12.8 is safe.

That being said, i would have said you woudl have 125ish rwkw based on your mods, which are very similair to mine.

First thing - the MACE tune that comes with the throttle body is a special tune designed to smooth out throttle response. It's not a performance tune.

Talk to Foamy (Greenfoam) as he has recently done a tune for me, with some very low end (sub 1000rpm) timing tweaks to ease off on the off idle throttle response. The rest of the tune is a very good performance tune, which seems to do well with my VT. I had to get the change points adjust as the valve springs were bouncing at abouit 6000 rpm but the damn things now so torquey it will chirp into second gear - and it's an auto - if the wheels arent dead straight.

BTW - Foamy if you read this, I need to redo the tune to suit a 3.46 diff in the next month or so. Hopefully you can correct the speedo as well as the shift points ?

Cheers

[holden_4aw_lyfe]

thanks Tsunamix,

i just emailed greenfoam then and explained everything, i hope he can do something for me...its upsetting knowing your cars not running right... im geting HSV blue top injectors as that might be the problem aswell, all these CAI mods might be putting too much air in and not enough fuel from the injectors....

please, any other suggestions or comments would be appreciated!

[Tsunamix]

I dont think injectors are your issue, because the factory injectors seem to be good until you go forced induction. That being said, if injectors help you, I might do the same :P

[billy bob]

Did you buy everything off mace all at the one time?
Is the chip written for all those mods?
If it is get on the phone and tell him your not happy

[holden_4aw_lyfe]

i usually put them in a week at a time. each mod gets a week to ease in before i go and put something new in. the mods bar the chip were in there before. do you think a tune will correct this problem?

[holden_4aw_lyfe]

tsunamix, im getting the hsv injectors so ill let you know if it helps

[Tsunamix]

On Maces TBODY Chip -

SOme facts - The factory throttle body has a cast in lump that provides specific air flow characteristics in the plenum. At small throttle openings, the casting provides a heap more turbulence, and slightly lesser airflow than you would expect. This has 2 effects - Efficiency is improved, and throttle response is dulled. This makes it a much smoorther drive in stop start traffic, and wastes less fuel at just off idle.

The MACE throttlebody has those lumps machined out. COnsequently Throttle response is very sharply improved. It's at the very limit for drivability in stop start conditions. So MACE's tune is designed to reduce response early in the throttle opening cycle, and nothing else.

This was stressed to me when I bought it. I tried the MACE tune and the factory tune, and found that with the factory tune, I was always accelerating too rapidly and braking to compensate. Bloody annoying. The MACE tune fixed this, BUT IS NOT A PERFORMANCE TUNE.

If you want to get drivability plus performance, talk to foamy.

[holden_4aw_lyfe]

but would the car run like crap after the throttle body is installed? the car runs like crap now...its like its confused with gear changing, it cant make up its mind with wich gear it wants to go into...

[billy bob]

With the mace throttle body there should be a little restrictor that goes in your vacuum line to correct the gear changes. Did you install that?

[holden_4aw_lyfe]

what does it look like?

[billy bob]

Go on the mace website. I think its on the last 2 pages of the installation instructions

[delcowizzid]

every time a mace throttlebody goes on it stuffs the shift points up they shift too early torque converter locks early etc due to the extra air going in at less throttle position so the ecu sees you are driving easy and shifts early but in reality you are driving harder than the ecu sees due to the TPS reading being different than stock for the amount of air going in..ive fixed so many that do it. i dont see how a restricter will do much being that its the low TPS reading that makes it happen.

[holden_4aw_lyfe]

thanks for your reply delcowizzid!

could you possibly do me a ECU?

Cheers!

[delcowizzid]

im away at the moment but i could when i get home in the next week or so

[holden_4aw_lyfe]

if you could that would be great. It would be nice to have a tune to suit the mods i have. Thank you so much delcowizzid!

[holden_4aw_lyfe]

delcowizzid are you back yet???

[MizzVR]

i was interested in this thread. did you sort your problem out?

[MACE]

We refunded Matt in full with the memcal as we normally do if people aren't happy with it, however after Matt installed one of our new 85mm MAF's the car seemed to run much better. This shouldn't be the case as going a larger MAF without a tune tends to make the car run worse unless the original MAF was sad (dirty???) which it appeared to be. In which case no mail order tune would have been able to rectify this!

On this note this is a good example why it's important to keep your MAF clean Clean your MAF