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-   -   940 problems with lazy start (https://forums.turbobricks.com/showthread.php?t=359839)

majkelos 04-07-2021 04:52 AM

940 problems with lazy start
 
Hello, this is my first post here;) but I am driving my 940 for a while already.
I've tried quite a few tips to solve my problem but with no luck. I am struggling with a very lazy start, it has really no power until 2500-3000 rpms, then the turbo kick in and it begins pushing me into my seat.
I compared it to other 940s mine is the laziest... even comparing it to stock ones... I'm sad :(

My setup:
- B230FB
- 531 head
- Vx3 cam
- 16T turbo
- 465ccm green injectors from S60
- custom fuel pressure regulator with 3.8bar
- walbro 255 fuel pump
- original spark plugs
- AW71 gearbox with accu mod
- rear axle gear ratio 3.73
- 3 exhaust no cat

It is really slow at the beginning - comparing it to stock B230FT or even stock B200FT. It is so slow it is impossible to do burnout which is very likely to happen on B230FT.
What could be wrong? Any tips appreciated.

hessam69 04-07-2021 05:12 AM

Could the cam belt be one tooth retarded?

majkelos 04-07-2021 05:24 AM

This is interesting. I need to check it somehow.

Fa182 04-07-2021 12:23 PM

Well there's not much happening below 2,500 on my B230FT either.
I'm also running a 16T at around 0,9bar.

Just an idea.
Are you running the stock Intercooler? That's quite a big limiting factor I've found after swapping to a 16T.
I was very disappointed because I've almost didn't notice anything.
It was only after upgrading to a KL Intercooler. See here: https://forums.turbobricks.com/showthread.php?t=343520

Also, how does your AFR look?
465cc injectors could be too big if you're not running a lot of boost pressure.
I'm still using stock sized injectors and they're plenty, AFR is perfectly fine with my setup.

EDIT: Are you using custom chips? I've bought a nice set from here and I'm very happy with them, gave a very nice upgrade.

majkelos 04-07-2021 04:48 PM

I am using custom chips - but I don’t trust’em. Maybe I should find the different ones. Do you have some trusted source for these chips here guys?
Regarding the intake - I’m running DO88s so the issue seems to be somwhere else.

Fa182 04-07-2021 05:53 PM

I'm using these: https://forums.turbobricks.com/showthread.php?t=355788
I got them back when he started making them, but Swedbrick now sells them here in Europe, so get in touch with him if you want.

Triebwerk 04-08-2021 03:18 AM

Could be a tired wastegate actuator. Had this situation a few months ago. Spool shifted 600rpm.

majkelos 04-09-2021 05:40 AM

Quote:

Originally Posted by Triebwerk (Post 6173821)
Could be a tired wastegate actuator. Had this situation a few months ago. Spool shifted 600rpm.

Hmm. Thanks. This might be an issue here as well. Is there any easy to find replacement for this or should I go for a brand new OE?

majkelos 04-09-2021 05:42 AM

Quote:

Originally Posted by Fa182 (Post 6173682)
I'm using these: https://forums.turbobricks.com/showthread.php?t=355788
I got them back when he started making them, but Swedbrick now sells them here in Europe, so get in touch with him if you want.

Thanks for sharing this. I will get in touch with him. Also I was thinking about buying an Ostrich 2.0 and some eprom burner and getting in touch with some shop who knows how to tune this engine. Unfortunately I am not aware of any garage like this in Poland..

majkelos 04-09-2021 05:44 AM

Quote:

Originally Posted by Fa182 (Post 6173574)
Well there's not much happening below 2,500 on my B230FT either.
I'm also running a 16T at around 0,9bar.

Just an idea.
Are you running the stock Intercooler? That's quite a big limiting factor I've found after swapping to a 16T.
I was very disappointed because I've almost didn't notice anything.
It was only after upgrading to a KL Intercooler. See here: https://forums.turbobricks.com/showthread.php?t=343520

Also, how does your AFR look?
465cc injectors could be too big if you're not running a lot of boost pressure.
I'm still using stock sized injectors and they're plenty, AFR is perfectly fine with my setup.

EDIT: Are you using custom chips? I've bought a nice set from here and I'm very happy with them, gave a very nice upgrade.

As for the AFR - on stock injectors and 1bar boost it was not very good, at the full throttle it was running lean mixture. I need to install some additional gauge and sensor in my exhaust, that's for sure.

Fa182 04-09-2021 06:28 AM

Quote:

Originally Posted by majkelos (Post 6174137)
As for the AFR - on stock injectors and 1bar boost it was not very good, at the full throttle it was running lean mixture. I need to install some additional gauge and sensor in my exhaust, that's for sure.

Just to be safe, did you reset the ECU (by clamping off the battery for a while) and let it relearn after turning up the boost, so it can adjust the fuel mixture accordingly?
LH 2.4 is capable of doing that to quite a bit of extent, more than people might think in my opinion.

If that doesn't help, the chips might help too.

I've used a set of chips from an unknown source with an unknown fuel map before (came with the gold EZK and had to use them because I broke a pin off on my old TLAO ones) and the AFR was absolutely all over the place, terrible.

I'm using -768 cream/white V70 injectors at the moment (because the old stock -804's were leaking), but they have the same flow rate (about 340cc) and on full boost I'm well below 11 on the AFR gauge.

Wilford Brimley 04-14-2021 04:49 PM

Quote:

Originally Posted by majkelos (Post 6174137)
As for the AFR - on stock injectors and 1bar boost it was not very good, at the full throttle it was running lean mixture. I need to install some additional gauge and sensor in my exhaust, that's for sure.

If you're using a narrow band that's basically useless info

redblockpowered 04-15-2021 02:08 PM

Installing larger injectors without tuning the car will often cause fairly significant driveability issues, especially at part throttle.

Wilford Brimley 04-17-2021 03:14 AM

So sounds like bigger injectors/no real afr/no tune is your problem...I mean it makes sense.

redblockpowered 04-17-2021 06:26 PM

Quote:

Originally Posted by Wilford Brimley (Post 6176465)
So sounds like bigger injectors/no real afr/no tune is your problem...I mean it makes sense.

Yeah that's what I'd put it down to. Doesn't sound like there's anything wrong with it beyond that.

mikep 04-17-2021 08:18 PM

If it boosts when you power-brake it, how does the torque converter feel if you do a stall test? The stator clutch could be freewheeling.

lummert 04-18-2021 12:11 PM

Does black smoke roll under boost? If yes, try lower fuel pressure. I'm running Bosch Gen III white composite body injectors on LH2.2 with 2.5 Bar FPR. With 3 Bar FPR it runs too rich.


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