Brett

I have run over 18 psi with my link and havent had a problem. But today when I put in my new DME chip and 84# injectors I hit overboost protection at about 12psi. Danno is working on a solution for me but it is the first time this has happened.

NZ951

FYI the max boost limit on the new Link G2 is 101.5psi

GPF

Despite applying the suggested fix to increase the physical fuelling and turn down the voltage from the Link box, I'm still no better off. I upped the fuel pressure to 4 bar, and ran Danno's chips on the heaviest setting. This allowed me to reduce the fuelling from the Link box to get the max voltage to the DME down to about 4.2v - but that didn't cure the cutout problem. (I've now gone back to lower FP/FQS delivery and increased the DME voltage again so it doesn't affect the timing btw).

I then started to suspect that it was a different problem that simply exhibited the same symptoms - maybe ignition breakdown/huge misfire somehow. I have worked my way right through the ingition system now though and have renewed everything - plugs, dizzy cap, rotor arm, coil and plug leads. No change though!! (Except to my wallet! )

I already gapped the plugs (BR7ES) a bit closer than standard. I'll close them up a little more just in case, but I'm now back to thinking it is still an overboost issue - but at lower voltage levels than expected?

I changed to an Apexi AVC-R to get more control over the shape of the boost curve, and I can now eliminate the cutout issue by reducing the boost between 4000 and 4500 rpm, and also at about 5500, but that only masks the problem and doesn't deliver the maximum power throughout the rev range does it!!

It's about time this got fixed - it's REALLY pissing me off now.

If Danno is still around I'll drop him a PM. Any other suggestions?

Regards

Graham

'88 Turbo S

UK952

Hi Graham,
Funnily enough my 18PSI guru chips exhibited a strange cutting out phenomenon, at around 18PSI in 4th and 5th gears. These were non MAP (im still running the barn door) but putting in my old 15 PSI ones I could run 18 PSI and recently due to a boost controller failure (I think its the wiring due to too much in the glovebox) I ran 24PSI without cutting out. I have also borrowed a later set of 18PSI chips and these were fine at 18/19PSI.
My 18PSI chips and Davids were produced at the same time and both cars exhibit 4th and 5th gear cutting out on a later set we borrowed there was no problem, i believe ours may have been from a bad batch how old are yours?

Tony

GPF

Hi Tony,

How's things?

From memory, I had them about a year ago - they replaced an earlier 15psi set.

Regards

Graham

'88 Turbo S

ewainwright

"Danno is working on a solution for me........"

If we only got a dime each time we've seen this statement :-)

UK952

Hi Graham,
Similar time frame, have you tried the 15's?
If that doesn't make any difference then 'refreshing' the engine and battery earths might also help,
Tony

jimbo1111

GPF it sounds to me that you problems maybe coming from running overly rich. Could you restate what injectors you have installed along with the rest of your setup? Do you have a device for monitoring a/f?

GPF

No, but I'll dig them out.

Problem is, I only have one of the two sockets that are supposed to be in the looms of most Turbo's (IA and RCP) that Danno tells you to bridge to select injector sizes on his standard chips, so I was always a little dubious about which set of maps were in use. The chips I have now are set for my injectors only and don't refer to those plugs at all.

Mind you, now I have wideband I can make sure the fuelling is OK so I'll give them a go.

Regards

Graham

'88 Turbo S

UK952

The injector sizing should be changed with the rotary switch on the board, I thought one of the plugs (region coding) was to do with ignition timing for race gas, and the other was an impedence adaptor plug (not sure exactly what this does)

Tony

GPF

Hi Jimbo,

OK :

LR DPW
Apexi AVC-R
Garret t04b 46 (SFR)
LR Stg I IC
Link AFM MAP conversion
K&N Panel filter
Guru custom chipset
Bailey DV30
Laust's VM
Ported & Polished Head
Widefire HG
Siemens 55's
NGK BR7ES's
AEM wideband

Oh, and now new coil, dizzy cap, rotor arm and HT leads (all OEM).

Unless my AEM is playing up the problem is not caused by running too rich. At full boost/WOT the AFR looks OK - it richens up from just over 13 at 3000 to about 12 by 5000.

If I keep the boost below 18psi all is OK - but anything much over 18 is likely to cause the cutout - which does feel like overboost to me. ie violent and sounds just like hitting the rev limiter.

It is most likely to happen between 4000-4500rpm, sometimes at around 5500rpm, but with the AVC-R I can just dip the boost slightly here and that fixes it.



Regards

Graham

'88 Turbo S

GPF

Ah, maybe you're right there - I just remember that I needed a combination of the RCP and IA plugs to select the correct maps for my setup. If they control the ignition maps I don't think I'll try them.

Thanks Tony.

Regards

Graham

88 Turbo S

UK952

OK hope it solves it, it sounds very similar to what we experienced I put the chips in Davids car first, whent through the leads / cap / cleaning the earths route it got a little better, put my chip in my car and also got the cutting out. Tried a different later 18PSI chip in both cars, both ran fine (and with smoother tickover) whent back to the 15PSI chip in mine it also ran fine.
Tony

UK952

Are you running ballast resistors with the 55's? Wont change the problem but might give your ECU an easier time, if you can solder not too bad too fit.
Tony

GPF

Hi Tony,

No I'm not.

(And I've got enough jobs that I'm already behind with without looking for more!!)

Regards

Graham

'88 Turbo S