325i throttle body on 320i

Thu Sep 13, 2007 2:56 pm

What chip did you say you had ?
Why did you use the 2.5 injectors ? I would have used the 2.0 ones but got them cleaned before fitting.

Thu Sep 13, 2007 3:03 pm

I have a Superchips chip (I got it for a reasonable price). The injectors that came out of the car worked fine. I think I misread a comment; looking back over the thread, nobody said that the larger 325i injectors were necessary.

I'm thinking of putting the old ones back in.

Thu Sep 13, 2007 6:22 pm

Personally, I'd.....
1) Change the chip for an A-Tech "wild" one.
2) Open-out the mouth of the original 320i inlet manifold and use it.
3) Go back to the 320i injectors.
Stuart.

Fri Sep 14, 2007 9:05 am

Cheers, Stuaty. I'm going to try putting the original injectors back in. The 325i manifold will have to stay, as I've opened up the inlet ports a little to accommodate it. We'll see...

Fri Sep 14, 2007 9:22 am

Fueling will be way out if you use 325 injectors and FPR. Change them for the 320 items.

Fri Sep 14, 2007 10:54 am

Well, on the rollers, the car wasn't overfuelling. But, yeah, I'm going to put the 320i injectors back on. I have an adjustable fuel pressure regulator anyway, so that should make it easier to find the best flow rate.

Mon Oct 01, 2007 4:58 pm

Hello All!

Right, I've put my old 320i injectors back on the car, and I have to say it does run pretty well. Power is up to a minimum of 115bhp at the wheels, arriving at 6,250rpm. Throttle response is up, and the engine feels as if it's far freer-breathing. Torque seems to have suffered, but if you wring it out in every gear, the car does feel quicker.

Got a new problem now though. There seems to be a problem with the TPS... Actually, the TPS itself works fine, it's the wiring that runs to it that's causing issues. If you disturb the wire, the idle rises to about 1300rpm (from around 750). Not good. Has anybody encountered a similar problem? If so, would it cause the engine mapping to resort to a 'limp mode' throughout the rest of the rev range? (The way the car drives woul likely suggest not) And is it a big job to replace the wiring? I'm no auto-electrician, and wouldn't know where to start...

Mon Oct 01, 2007 5:18 pm

Stylescribe wrote:Has anybody encountered a similar problem?

I have.
I thought it was a wiring fault because if I wiggled the wire the idle would return to normal. So I re-made the loom back as far as the engine loom.
It made no difference.

I replaced the TPS with a brand new one (Ã‚£46 from BMW IIRC) and it cured the problem.
HTH
Stuart.

Mon Oct 01, 2007 5:27 pm

Thanks Stuart. So, you had the same problem? It's annoying. The idle would occasionally fluctuate with my old TPS, but not like this.

Did the running of your car improve with the new TPS? Mine seems to drive fine, but I'm just concerned that, after all the time and effort of the throttle body conversion, this little fault could be affecting performance.

Mon Oct 01, 2007 5:29 pm

Stylescribe wrote:Power is up to a minimum of 115bhp at the wheels

I'd call that a result. It's got to be 140 at the flywheel. As I posted earlier in this thread, I'd change the chip too, or get it re-mapped.

Mon Oct 01, 2007 5:42 pm

Yeah, I'm pretty pleased. That figure was achieved with standard unleaded. Performance seemed noticeably improved with a full tank of Shell V-Power.

I can't really afford to change the chip for now. And to be honest, the car does drive very well with the Superchips chip. I'd recommend this conversion, for sure.

Mon Oct 01, 2007 6:03 pm

If you're happy, that's all that matters!

:D

Mon Oct 01, 2007 6:08 pm

Stylescribe wrote:Did the running of your car improve with the new TPS? Mine seems to drive fine, but I'm just concerned that, after all the time and effort of the throttle body conversion, this little fault could be affecting performance.

The old TPS had a fault at wide-open throttle too. It wouldn't rev above 5k, it backfired and once the revs had dropped, it would run fine again until the next time I revved to too hard.
It was 2 seperate faults in the same TPS, though.
It didn't seem to have any bearing on how the engine ran generally, just intermittant idling and WOT.

Tue Oct 02, 2007 10:02 am

Cool, that helps. Mine revs to 7,000 (when the occasion demands...), so it would appeat that it's just the idle that's affected.