VEMS Engine management systems, plug & play ECU upgrade

[PhilKent]

Resurrecting and hopefully bringing this post back on track, a question/conundrum for the collective:

I’m running a std block with stage 1 intercooler, custom 3” exhaust and downpipe VEMS with wasted spark, LR recirc valve, LR Super 53 8# P trim turbo 3bar fuel rail with 630cc/min injectors. I have been running the LR DPW for years on MBC, but have struggled with EBC setup and boost creep at high RPM, so swapped it for a Tial F46 recently. My problem is that the Tial is apparently causing wild boost surge and not controlling the boost at the expected spring pressure (fitted it with 1bar spring initially with overboost everywhere, then 0.6bar spring which is now giving this boost surge). See the picture for a snap of the boost surge (this is not overboost fuel cut).
It is not a vacuum/boost line setup issue or leak, I know the config for the LR and tial gates. I’m not currently trying to control boost, just let the gate do its thing. I’ve statically checked the gate and it appears to operate as expected (albeit slightly higher pressure than the published figures, but within tolerance). You can see from the image that the gate is cracking open at about 70-80kPa as expected, but then not controlling the boost at that level.
I suspect a dodgy gate but can’t understand how or why. Has anyone else ever come across a similar issue? I will be re-fitting the LR gate next week when I can get hold of a std dump pipe again (after modifying my current one to fit the tial).
Worth noting that I've run the car with the wastegate dumping into the exhaust as normal, and also dumping to atmosphere (very noisy!) to check if there was a back-pressure issue. It made no difference to the surging issue.

 

[944Turbo]

So are you running with the ports open to atmosphere and just the spring holding it shut?

If so the only thing I can think of is it backwards? (manifold pressure pushing the valve against its seat not away from its seat?)

If that is correct apply pressure to the open port and see how much needed to open it - you can get a rough idea with a footpump with the wastegate out of the car - possible with it in the car in your vent to atmosphere set up.

Tony

 

[TTM]

You mention boost surge when running the Tial with the 1 bar spring, was this also whilst running the WG on the spring alone, without any interference from either your EBC or MBC?
If as you say you have everything plugged correctly then I would imagine that perhaps the WG is too large and needs a spring even softer than 0.6 bar to smoothen its "response signal" - fancy engineering term to pretend I know what I'm talking about.
For what it's worth I have always run a 38mm Tial, either in bolt-on or v-band form, and got boost control really smooth, even with my 3L 16V engine now, with a spring no bigger than 0.4 bar. EBCs work better with softer springs and it was simply impossible for me to get any proper boost control at all with the 1 bar I ran the WG with originally.

 

[PhilKent]

Tony, you got it spot on sir, well done! After swapping back to my LR gate for a session at CAT driver training, I sent a message to tial with photo's of my setup. The plumbing lines were correct, but I hadn't realised the gate itself operates opposite to the LR (or stock) gate (I feel like a Muppet already so no need for sarcasm folks!). And in fact the tial won't fit in the 'correct' orientation without more mods to the exhaust (I have the early turbo so no adjustment in the short elbow to the gate).
I've ordered parts and a mig welder and plan to do the mods myself after spending small fortunes with garages doing not great welding mods to the current exhaust. It's fun learning to weld stainless steel
Can't be sure yet, but I think this should solve the issues! Tested the gate in static mode and it operates as per tial instructions...

 

[Waylander]

You might find MIG and stainless hard work, TIG is the normal thing for stainless

 

[PSH]

Hi Phil...as Martin said TIG is the preferred route, you need to purge the pipe with Argon too..you can buy special end plugs for doing this

Pete

 

[944Turbo]

Tony, you got it spot on sir, well done! After swapping back to my LR gate for a session at CAT driver training, I sent a message to tial with photo's of my setup. The plumbing lines were correct, but I hadn't realised the gate itself operates opposite to the LR (or stock) gate (I feel like a Muppet already so no need for sarcasm folks!). And in fact the tial won't fit in the 'correct' orientation without more mods to the exhaust (I have the early turbo so no adjustment in the short elbow to the gate).
I've ordered parts and a mig welder and plan to do the mods myself after spending small fortunes with garages doing not great welding mods to the current exhaust. It's fun learning to weld stainless steel
Can't be sure yet, but I think this should solve the issues! Tested the gate in static mode and it operates as per tial instructions...

Glad it is on the way to being sorted - If you can get the parts off taking them to a welding specialist should give better (and probably cheaper) results than a local garage - not easy to remove the early cross pipe though - has anyone tried to modify one?
Tony

 

[PhilKent]

Wastegate in place and normal operation has resumed! In fact improved operation is clear now. boost can be controlled nice and steady near the limit of what I wanted and with no mild transient oscillations. Basic tuning of the ref dc versus rpm has been done and all looks good.
As for the welding, stainless mig was no bother at all. Much easier than tig in my experience as an amateur. Obviously not as tidy, but that's what and angle grinder is for!

 

[944Turbo]

Excellent, well done!

 

[PhilKent]

Thanks Tony, a picture of it fitted. I'm quite chuffed with my welding skills for a first timer. It all survived a great day out a Goodwood on 1st November my first ever track day in the 944 in nearly 20 years of ownership.

 

[PhilKent]

Note, the wastegate pic previously posted - the top left (outflow) is the garage welding, the bottom right (inflow) is my attempt, all tidied up with an angle grinder of course!. Below is a static pic of the car at goodwood, unfortunately no dynamic pics...

 

[PhilKent]

There's lot's of posts for 'Turbo engine re-builds' on the forum this past year... I'm doing the same following my Goodwood run in November 2021. I took the engine out February 2022. I got a reminder picture today, so it's been a full year (see below). Still in pieces on the garage floor, but I've almost amassed all the bits to put it back together. Following various 'challenges', my tack has changed a bit. I spent time porting/polishing and building an 8v N/A head converting to turbo valves etc which is now sat on the shelf with the other two heads I've got! I've since been doing a similar port/polish and build on a 16v S head which I'm now going to be using. Currently awaiting the return of the pistons which are being cut for valve reliefs to run the 16v head...

 

[scam75]

Good luck, I'm one of those that have "been there" recently!

Stuart

 

[Eldavo]

Never has so much pain been summed up into the one word "challenges”. Home stretch now.

 

[PhilKent]

Bending your ear has been helpful David, thanks. The guy doing the pistons seems to be struggling with the task a bit, I've given him a template piston, a CAD drawing file and a scrap piston for trials. Fingers crossed they come back good to go...

 

[blade7]

The guy doing the pistons seems to be struggling with the task a bit, I've given him a template piston, a CAD drawing file and a scrap piston for trials. Fingers crossed they come back good to go...

Interesting picture, I'll compare it to the Wossner 3.0 16V turbo pistons I have from Hartech.