detonation

General Chat And Help Regarding Turbocharging and Supercharging.

Moderator: phpBB2 - Administrators

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

detonation

Post by gilps »

Hi Guys looking for bit of advice.
I have Tvr Griffith 500 that has been supercharged rotrex supercharger running about 6psi bosch green giant injectors mapped omex ignition all set up by Mark Adams. The car runs great silly power very smooth 99% of the time.

The only issue I have is I am getting detonation, the detonation only seems to happen when the car has been running for a while in slow traffic and then is opened up when you get a clear road. I assume that the engine is getting hotter in the slow traffic and this is the cause of the detonation as all other times I experience no detonation.

Firstly does this sound feasible and if it does what is the best remedy to keep it cooler while running in traffic. Do additives like waterwetter work to help or would I be better getting a lower temperature fan switch?
Is there another possible cause for the detonation?
Any help or advice would be great.
Chris



DaveEFI
Gold Member
Gold Member
Posts: 4603
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI »

Sounds like it wants a bit more fuel with high under bonnet temperatures. Do you have a wideband lambda sensor fitted? If so, can you do a log of things when the detonation occurs?
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

DaveEFI wrote:Sounds like it wants a bit more fuel with high under bonnet temperatures. Do you have a wideband lambda sensor fitted? If so, can you do a log of things when the detonation occurs?
Many thanks Dave for the response. i dont have a wide band lambda set up on the car but when it was being RR set up the AFR was set to 12.4: 1 at WOT I have also tried increasing the fuel pressure a bit which should in theory richen the fuel mixture up a bit but this makes no difference. The car was on the RR for a good few hours with multiple runs on one of the hottest days last year and at no point did it show any signs of detonation. I dont know if this makes any difference but the car was set up in 5th gear because even with the boot loaded with steel weights it was just spinning up on the rollers, it was spinning up in 5th but he managed to get it all sorted. The only other point is the car was set up with the bonnet removed (intake not taken from under bonnet) but the engine will have been running cooler with the bonnet removed so perhaps this was part of the issue.

The car is running really sweetly so I dont want to mess about with the fuelling too much if possible and as I have said its only on rare occasions when the engine is at higher running temps that I experience any pinking.
Whats opinions on water injection?
Chris

User avatar
Rossco
Moderator Gold
Moderator Gold
Posts: 850
Joined: Sun Nov 19, 2006 11:33 am
Location: Too many to even keep count

Post by Rossco »

My first reaction would be to ditch the Mark Adams kit and go MS or VEMS

Failing that then as stated more fuel wouldn't go amiss

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo »

Detonation is bad tuning....

Except of course if some other problem has developed thereafter.

But presumably you're saying you can actually hear this from inside the car...which means it's really bloody bad detonation ( not that any is ever good )

So...6psi is very low, does this even have an intercooler ? or no ?

Whilst 6psi is low....and potentially no intercooler, IMO 12.4 really is pushing the boundaries of running lean.
If it was 6psi and absolute certainty of cool charge temps, and absolute certainty each cylinder was no leaner than that...then perhaps it could be ok.

He probably was not monitoring every cylinder though. Are charge temps being monitored and factored in to the tuning ?

Sure you're using the correct fuel at all times ?

With no wideband fitted now ? are you sure mixtures are still at that same level they were when tuned before ? ( I wont ask if they're still good...as I feel they should be richer anyway for all the above reasons )


Certainly water injection is an option, but you'd need to find out what the actual cause is first. And at only 6psi...some water injection is likely to cost power too.
A little more fuel might help, a little less timing under those circumstances, or es water injection ( or a better...or fitment of an intercooler depending on what charge temps are like )
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

Coops
Site Admin
Site Admin
Posts: 6317
Joined: Fri Nov 17, 2006 7:43 pm
Location: Newbury, Berks
Contact:

Post by Coops »

As stevie said you are using the correct fuel? super unleaded all the time?
One thing I was told I had to use once I converted over to a supercharger was super unleaded fuel.
Regards Tony C (COOPS)
Image
MS2 V3.57 Ecu mapable efi and wasted spark ignition.
Procharger D1SC supercharger and Cossie RS500 Intercooler @ 14psi of Boost. 416 RWHP, (boost leak)
Forged 4.8 V8 kitted out with the dogs Cajones of parts. :D
Sponsored by: www.v8performanceparts.co.uk, www.interpart.biz, www.caprisport.com & www.baileyperformance.co.uk

DaveEFI
Gold Member
Gold Member
Posts: 4603
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI »

IMHO, a wideband lambda sensor is essential.

One of the snags with rolling road only setting up it is it can't reproduce all the conditions you'll get with road use.

I'm not familiar with Omex - except that it's very highly regarded - but it very likely will have correction for high intake air temperature. That's what I'd be looking at. Altering the fuel pressure is not the way to go, as it effects all the mapping under all conditions. But without a wideband, you're working blind.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

DEVONMAN
Top Dog
Top Dog
Posts: 1440
Joined: Sat Dec 13, 2008 2:46 pm
Location: Croydon UK

Post by DEVONMAN »

As Dave EFI has said the air intake sensor may be leaning the mixture in such situations. Heat soak in traffic conditions may be influencing the sensor and leaning the mixture until a correct air flow temp is sensed.
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!


Image

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo »

DaveEFI wrote:IMHO, a wideband lambda sensor is essential.

One of the snags with rolling road only setting up it is it can't reproduce all the conditions you'll get with road use.

I'm not familiar with Omex - except that it's very highly regarded - but it very likely will have correction for high intake air temperature. That's what I'd be looking at. Altering the fuel pressure is not the way to go, as it effects all the mapping under all conditions. But without a wideband, you're working blind.
It most certainly will have the option, whether it's used or installed or tuned correctly is another matter.

That said...if it has run for 2 years without issue, could look elsewhere for issues
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

Many thanks for all the info. The Supercharger was fitted about 6 years and 10,000 miles ago and has an inter cooler. I only purchased the car last year from a chap who had emigrated to the USA so had to deal with his Sister who knew nothing about cars I did notice the pinking fairly quickly hence having now spent somewhere in the region of £2500 trying to get it resolved. This has included new fuel pump and new wiring to the pump, Omex 200 mapped ignition new throttle pot sensor, new Bosche Air flow meter, new adjustable fuel pressure regulator to keep the pressure at 3.0 bar without Vac and 2.5 bar with Vac. All induction pipes have been lagged to try and keep the intake temps as low as possible, re-routing the intake pick up to get a constant cold feed of air. Having the car fully set up on a RR by Mark Adams who is supposed to be the best at tuning these engines. I have checked all the mechanics of the engine compressions are good at around 150psi per cylinder, spark plugs are a nice shade of light grey I have had an endoscope down all the spark plug holes and the bores are nice still showing some honing marks. Piston tops are relatively clean with little carbon build up. Cam looks in very good condition although I have no idea what cam is fitted I do know it was changed about 15k miles ago. You can run the car all day and it will behave perfectly no pinking super smooth etc etc. Then all of a sudden you put your foot down and its pinking like hell very loud I obviously take my foot of the power straight away. The only common factor to the pinking is that it seems to be when you put your foot down after its been running for a while in slow traffic and the temps are higher . I don't get any fault codes on the ecu it also only does it at WOT over 4k rpm it never pinks under load at low speeds in high gears even when labouring the engine. I was in the car on Sunday i did about 100 miles and it it only did it once near the end of the run. Always run the car on super unleaded 97 octane. I don't have a Shell garage local to me to run it on 99 but that may be worth a try.

So fitting a wideband seems to be the next step. Could this be fitted post Cat as the only other way for me to fit it would be on the exhaust manifold so would really need to fit two. Plus getting the manifolds off to fit it would be a major major task, fitting post cat at the bottom of the Y piece would be far easier.
Chris

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

stevieturbo wrote:Detonation is bad tuning....

Except of course if some other problem has developed thereafter.

But presumably you're saying you can actually hear this from inside the car...which means it's really bloody bad detonation ( not that any is ever good )
Yes the detonation can be heard very clearly from inside the car and the car is very loud

So...6psi is very low, does this even have an intercooler ? or no ?

Yes intercooler fitted

Whilst 6psi is low....and potentially no intercooler, IMO 12.4 really is pushing the boundaries of running lean.
If it was 6psi and absolute certainty of cool charge temps, and absolute certainty each cylinder was no leaner than that...then perhaps it could be ok.

He probably was not monitoring every cylinder though. Are charge temps being monitored and factored in to the tuning ?

Yes there is an intake air temperature sensor but this is only for the ignition not the fueling but I could set it to retard the ignition as intake temps increase

Sure you're using the correct fuel at all times ?

Always use 97 super unleaded no local garage to me for 99 but could travel to see if it sorts the problem out

With no wideband fitted now ? are you sure mixtures are still at that same level they were when tuned before ? ( I wont ask if they're still good...as I feel they should be richer anyway for all the above reasons )

If anything the fuelling should be richer than when it was tuned as I have increased the pressure from 2.5 bar to 3 bar but this has made no difference the narrow band lambdas sort the fuelling out while in closed loop but an increase in fuel pressure should richen it up whilst in open loop


Certainly water injection is an option, but you'd need to find out what the actual cause is first. And at only 6psi...some water injection is likely to cost power too.
A little more fuel might help, a little less timing under those circumstances, or es water injection ( or a better...or fitment of an intercooler depending on what charge temps are like )

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo »

£2500 !!!! :o :o :o :o

That's mental. If this is a repeatable scenario, it should take any decent tuner a relatively short amount of time to resolve.

And if it is not repeatable on a dyno, then this was a total waste of money....but if you explained the problem to the tuner, again, any tuner with half a wit should have been able to make adjustments based on experience and what they've seen whilst tuning.

And again...it's the tuners job to ensure any adjustments for charge temp are sensible, whether that's fuel or spark.
Although after googling....it seems you are using 2 ecu's here. One for fuel and one for ignition ?

I've no idea what can or cant be done with the OEM ecu, so perhaps there are strange limitations here. But in the trouble areas you should easily be able to pull some timing to see if that fixes the problem.
Even as a brief test just pull say 4deg off the entire map and see if it's sorted, and if so you can re-tune to suit.

And certainly driving a few miles to try some 99...would have been cheaper than £2500 !!

And you can fit a wideband to one bank...of course it will only give info for that bank. Which is fine. If all is well there, then swap it to the other side. That in itself might be helpful anyway, rather than taking an average reading from all 8.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

Yes I must say im pretty pissed off with this situation. The main reason for getting the car RR set up was to eliminate the detonation which was explained in detail to Mark. The main issue is that the 14cux ecu can only really be set up by very few people and Mark Adams was recommended to me as the go to guy. in hindsight now I should have just ditched the old system and started with a completely new set up that could be tuned by more people. Mark has said that he will try and help sort this but he is 200 miles away and very hard to get hold of either that or he is now trying to ignore me.

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo »

gilps wrote:Yes I must say im pretty pissed off with this situation. The main reason for getting the car RR set up was to eliminate the detonation which was explained in detail to Mark. The main issue is that the 14cux ecu can only really be set up by very few people and Mark Adams was recommended to me as the go to guy. in hindsight now I should have just ditched the old system and started with a completely new set up that could be tuned by more people. Mark has said that he will try and help sort this but he is 200 miles away and very hard to get hold of either that or he is now trying to ignore me.
I would think the software for the Omex igntion is fairly simple.

So I'd just pull say 4deg off the entire map...and see how it goes from there.

What is it using as a trigger system ? Is it reading off the dizzy or a crank trigger ?

If timing alone cannot resolve the issue...then going for a proper fuel/spark management system will make a lot of sense, and certainly be far more flexible.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

omex uses a trigger wheel of the crank and yes I can knock off 4deg fairly easily just to see what happens. I could also have the omex plugged in and see what the intake temps are reading when its detonating if these are high at that time I can set the omex to retard the ignition automatically and revert to normal once the temps come down.
i also do have a way of checking the afr with an old Inovate LM1 wide band lambda that jut sticks up the tail pipe its not going to be 100% accurate but should give me an idea of whats going on. I have used it to set up carbs with very good success in the past.
Many thanks for your input help and advice it really is appreciated
Chris

Post Reply

Return to “Forced Induction”