Naplesguy06

Man, I wish I had a dollar for every time this has been brought up since 2002,it's likely over boosting. The owners manual even says this will happen for safety purposes if your boost levels exceed factory tuning,which many other variables can cause this as well as John and Tom mentioned. Typically, this is a protection default setting mapped into the ECU. The reason you don't see this as Much in the lower gears is because your typically out shifting the computer before it learns of the condition,in the higher gears motronic catches up and cuts the WOT fuel map to save the engine from leaning out and ruination. Good chips won't do this and overboost limits are either removed or you can dial them in yourself. The car likely has old early version APE chip clones,many companies copied APEs software back in the day and just put their own stickers on the chips. The early APE chips with banjo did not raise the boost levels beyond 14.9 or one BAR approxamitely and this happened often.They worked great as long as you don't exceed 15 psi in the higher gears. I have used them with the banjo or a MBC and find them all to be lean up top unless you run a 3 bar fpr.

Northern_aqs

Thanks to all for the valuable feedback and suggestions.
I have pressure tested the intake system as per the Clark's garage instructional and did not find any leaks of note. I was hoping to resolve this issue prior to beginning work on it for the winter lay-up and I believe I have identified the issue as a crusty connector on the harness side of the reference sensor. It was confusing as to why the harness would become an issue at peak boost only, but it makes sense when checking continuity while wiggling the harness.

I'm currently fabbing a low tech-low rise lift/ramp for my garage but when I'm finished this week I'll begin work on the following:

Ultra mount installation
Rod bearings
3.0 FPR
MSD Blaster coil
Power streering pump rebuild
Rack replacement
Reference sensor and fuel injector harness replacement
After market waste gate: haven't decided on a Tial or Lindsey dual port
Cat-delete and 3" exhaust fab.

I am leaning towards ordering a VEMS system to replace both the DME and KLR and eliminate the AFM, however I have yet to read anything from actual users. I like what I've seen of the VEMS software and the data logging and programming features built in, however I'm still firmly on the fence. The goal for the car is moderate performance upgrading with reliability. I will be keeping the 26/8 for now, as it "isn't broken" (yet) with no shaft play and seemingly little smoking. If I can achieve 300 rwhp at the 15 psi level, I'll be happy for now. Certainly the unknown origin chips won't be part of the car's future. I am open to advice and suggestions.

Tom M'Guinn

What's my prize for calling out the ignition and speed/ref sensors connectors? In your second video, it's clear the ignition was cutting out at idle too, so it wasn't "just" a boost thing. Hard to see how it cutting out could be directly related to boost (assuming it's that connector) but the engine does vibrate more and create more electrical noise when the rpm's and boost go up, so it might be that simple. At any rate, if the idle stumbles at all when you wiggle the connectors, its time to change them even if your original problem is unrelated. It would be good news if the frayed wires are limited to the connector side, but I'd peel back the rubber boots and take a good hard look at the harness side before concluding they are fine. 944online, LR and other places sell replacement harness patches that work great. I'd getting running right before digging in on the bearings and such. Otherwise, it will just be harder to sort out the issues (and their source) after major surgery...

Northern_aqs

Thanks Tom, you do indeed win the prize. The harness side is indeed the crusty side, it appears the reference and speed sensors were replaced at some point in the past. I'll be replacing as many sections of harness as available. No reliability is assured by cheaping out on these sorts of things. I'm not certain if the new harness is soldered to a pigtail cut at the computer end of the plug or if new harness has a pin end that can be inserted into the plug. There is no clear indication on Lindsey's website so I'll need to give them a call.

Hopefully I can reassure myself that the problem is fixed after fixing it without driving the car; we already have 6" of snow on the ground and it'll be here until spring.

Tom M'Guinn

Lindsey has instructions online -- see below. No soldering needed. They give you an assembled patch where you plug the pins directly into the main DME connector.

http://www.lindseyracing.com/LR/Parts/REFINSTALL.html

944online sells a similar patch harness.

I wasn't accounting for your winter when I said to fix the known problems first -- we get a little snow here maybe every two or three decades.