ENGINE STALLS ON 3rd GEAR WHEN TURBO KICKS HARD!

[nissias]

My car was ready yesterday with its brand new exhaust system from turbo till down to the backbox. We made an alternative for the "stiffy" as my car has a/c and the pipe should have gone a different way. Well obviously the car is much much faster than before. It goes fine on 1st gear with a lot of wheel spin when the turbo kicks, then perfectly on 2nd gear, then on 3rd gear going hard on the throttle after the turbo kicks the car suddenly stalls (there is a kick and suddenly the engine switches off but turns on right up as the car is moving), the engine light goes on and then off after 5-10 seconds and the car drives ok. I tried to rev it with 3/4 throttle and the engine did not stall at all. What do u think? I need bigger injectors maybe as we get more boost from the better downpipe and whole exhaust system? I surely can see the boost going up much more quickly than before. Let me know of your opinions

* P.S * The car was fine with stock downpipe and 2 inches exhaust system (pipes and backbox) before I took it at the mechanic.

[Leung]

Overboost?!

[ailwyn]

the engine light goes on

Have you found out what CEL code has been stored?

Ailwyn

[Candles]

With this one, I don't think you even need to check the stored fault code: You've put on a new high flowing exhaust, it is much quicker than before and guess what: You've got 'boost creep'. This is where the wastegate isn't allowing enough exhaust past the turbo to control the boost level so the boost pressure just rises and rises, out of control of the ECU.

Luckily the ECU has a safety feature to prevent this destroying your engine. When it senses more than 0.92 Bar it cuts the fuel to the injectors, giving you the symptoms you are seeing. It then keeps the check engine light on for about 30s and limits the RPM to 4000 (from memory).

The solution is to port the wastegate and/or install a device that raises the level at which fuel cut occurs. This could be either a reprogrammed ECU chip or a piggyback device that fools the car into not cutting the fuel. Search for 'porting the wastegate' 'everest' and 'FCD' on the forum and read all about it.

Candles.

[ESM]

A chip might not help - I don't remove the cut (I could but I don't) and my chips raise the fuel cut only slightly from 0.92 to 0.98bar. So if the creep takes you you beyond 0.98bar you need to consider other options. The only thing candles didn't mention is that it has been posted in the past that putting a 2" gasket into one of the exhaust unions will fix boost creep...

[nissias]

I think it's simply overboost and I need the MOTEC M400 on.
I'll take the car to the mechanic on Monday and see if that's the case.

[nissias]

the engine light goes on

Have you found out what CEL code has been stored?

Ailwyn

How can I check that?
I have no clue at all

[nissias]

:agree:

A chip might not help - I don't remove the cut (I could but I don't) and my chips raise the fuel cut only slightly from 0.92 to 0.98bar. So if the creep takes you you beyond 0.98bar you need to consider other options. The only thing candles didn't mention is that it has been posted in the past that putting a 2" gasket into one of the exhaust unions will fix boost creep...

Do you think that I can solve this problem by getting a good wastegate for the turbo?

[nissias]

I have 3 choices:

1) Get a good wastegate that would regulate the pressure not beyond the 0.92 bar limit and thus the engine will work on safe limits

2) Get an FCD that would probably damage the car as it would work overboost and beyond safe limits

3) Get a Motec M400 installed that would allow the car to work as it should but yet would still have overboost and thus might cause damage to the engine.

I believe the best solution is the first one with the better wastegate as I want my engine to work safely.

Isn't it weird though that overboost happens on 3rd gear and not on either 1st or 2nd?

[Monty]

Look here for how to check for codes http://lotuselancentral.com/repair/aldl.htm

nissias, thought u did a turbo upgrade? if so don`t understand how u weren`t over boosting to start with.

[Candles]

Overboost doesn't happen in 1st or 2nd as there isn't time with the rapid rev rise for the boost to develop. It takes time in the gear with full throttle for the turbo to 'creep' up and produce the extra pressure. You'll find it happens in 4th and 5th if you get the RPM high enough as well!

The best solution is, as you say, getting a better wastegate as this will allow whatever electronics you have now or fit in the future to actually control the boost rather than it 'creeping' away out of control. Aside from actually getting a better wastegate, you could actually port the current wastegate. See
http://lotuselancentral.com/forum/viewtopic.php?t=5732&postdays=0&postorder=asc&start=80

For the details including a great picture from Dico with his thumb.

Candles.

[nissias]

Overboost doesn't happen in 1st or 2nd as there isn't time with the rapid rev rise for the boost to develop. It takes time in the gear with full throttle for the turbo to 'creep' up and produce the extra pressure. You'll find it happens in 4th and 5th if you get the RPM high enough as well!

The best solution is, as you say, getting a better wastegate as this will allow whatever electronics you have now or fit in the future to actually control the boost rather than it 'creeping' away out of control. Aside from actually getting a better wastegate, you could actually port the current wastegate. See
http://lotuselancentral.com/forum/viewtopic.php?t=5732&postdays=0&postorder=asc&start=80

For the details including a great picture from Dico with his thumb.

Candles.

There is a variable boost controller from APEXi that can control the boost differently in every gear. I might try that so that I won't lose power from 1st, 2nd gear while it can correct 3rd, 4th and 5th gears working at the right boost with the engine stalling. Has anyone tried this Digital AVC-R Boost Controller from APEXi?

[GeoffSmith]

Overboost doesn't happen in 1st or 2nd as there isn't time with the rapid rev rise for the boost to develop. It takes time in the gear with full throttle for the turbo to 'creep' up and produce the extra pressure. You'll find it happens in 4th and 5th if you get the RPM high enough as well!

I appear to have overcome Peco induced overboost with Everest. I haven't confirmed it categorically but my thinking is along the same lines as Candles; the Everest gives increased mid-range boost so you're quicker up the revs and change up before boost creep takes hold. Has anyone had the balls to induce boost creep in 5th?

Geoff

[Dovey]

Digital AVC-R Boost Controller from APEXi?

Sounds expensive. Do yourself a favour and get one of Alans chips, he's being very modest. Since I fitted a kili, its cured the overboost from the big exhaust. They are the nuts

[nissias]

Digital AVC-R Boost Controller from APEXi?

Sounds expensive. Do yourself a favour and get one of Alans chips, he's being very modest. Since I fitted a kili, its cured the overboost from the big exhaust. They are the nuts

I do have Alans chip on my car but it is a v3.0
Does the newer v4.3 cure overboost? I know he is also trying to release an even newer version now that will allow the car to run with a richer mixture. Please advise

[ESM]

Digital AVC-R Boost Controller from APEXi?

Sounds expensive. Do yourself a favour and get one of Alans chips, he's being very modest. Since I fitted a kili, its cured the overboost from the big exhaust. They are the nuts

I'm glad it worked for you but I think you just got lucky. Your maximum boost with creep must have fallen between 0.92 (standard fuel cut) and 0.98bar (chipped fuel cut) to be cured by a chip. Its not going to work for the bulk of people who suffer with this problem.

[ESM]

Buying an aftermarket boost controller won't achieve anything. If you unplug the BCFV completely you'll still get boost creep. Its caused by the fluid dynamics in the turbo/wastegate/exhaust which is why real fixes always involve something that modifies the flow characteristic in the exhaust. So unless you stick the Apex up the tailpipe....

[nissias]

What do you believe I should do then?

[ESM]

Either

1) Port the wastegate

or

2) try the 2" gasket I mentioned above

or

3) try another exhaust

[nissias]

I think I might try porting the wastegate as this was the first thing that came on my mind and since you recommend it too i'll talk to my mechanic on Monday about it. Will the performance drop though on 1st and 2nd gear where I have no problems at all by doing this?