Detonation why?

[taz turbo]

I understand the cause of detonation, but could anyone explain my symptoms.

The car (turbocharged 2.8 V6 ford cologne) was on a rolling road, low/mid 30's ambient, producing 260+ BHP / 270 Lb/Ft no problems, but as soon as I leave the RR, I'm suffering from some detonation (as I was on the journey to the RR). Its nothing thats happened at the RR, but why detonation on the open road with far lower ambient and superior cooling?

Regards,

Chris.

[stevieturbo]

What tuning method ?

What type of rollers ? Are the same boost pressures being seen ?

How are you controlling fuel/timing ??

Some dynos have excellent airflow, so air temps might be as low, or perhaps just better controlled than on the road.
Others dont.

Some dynos simply dont load the engine up the same as will be seen on the road....so can always give a true optimal road map.

Final road tuning should always be done IMO..

[taz turbo]

Thanks for your prompt reply Stevie,

I don't want to name names, but was a very well respected tuner in the Manchester area

stevieturbo said:

What tuning method ?

A. A power run, checking emissions, inlet temp and a dizzy swing between runs.

stievieturbo said:

What type of rollers ? Are the same boost pressures being seen ?

A. I have a note of the make of roller somewhere, but not to hand. Boost pressure yes always constant ~7 - 7.5 Lbs

stievieturbo said:

How are you controlling fuel/timing ??

A. Fuel, std Bosch K Jetronic, with a micro dynamics petrol injection computer, enriching fueling whilst on boost. Timing Std motorcraft ignition with modified dizzy weights, and a micro dynamics EMS5 retarding the ignition whilst on boost.

stievieturbo said:

Some dynos have excellent airflow, so air temps might be as low, or perhaps just better controlled than on the road.
Others dont.

A. In my opinion the airflow from the RR was exceptionally poor, 1 mobile fan unit about 18" diameter. The temp in the workshop was around 33-35 degrees due to workshop doors having to be cosed due to neighbours.

I understand the 'choices' of the fuel/timing are far from ideal, but it's a very interesting car in TVR terms, and I wish to retain the originality.

I'm fighting it a little at the moment as, after the engine was rebuilt (about 2 years ago) I quickly (instantly) found out one of the big valve head was cracked, I replaced the heads, ran fine for quite some time then one day after 'booting it' it started running badly and using coolant. I should get the offending head off today to see if its HGF or a cracked head. Don't see why it should be HGF as I used Felpro gaskets on lightly skimmed heads and a flat block with ARP studs and had the heads wire ring grooved and fitted wire. All will be revealed later today, then more questions will no doubt arise.

Chris.

[Steve_D]

I hear you saying you want to retain the cars originality but I think you know that you have too many disparate systems trying to control the beast.

A single ECU (choice of make or model has been done elsewhere) will, I think, make all the difference. If you go for Megasquirt you can do the mapping yourself on the road.

Steve

[taz turbo]

Steve_D said:

I hear you saying you want to retain the cars originality but I think you know that you have too many disparate systems trying to control the beast.

A single ECU (choice of make or model has been done elsewhere) will, I think, make all the difference. If you go for Megasquirt you can do the mapping yourself on the road.

I'm agree that updating the control systems by 25 years would make an improvement, but to reiterate its not an option. The car is a pre-production prototype, that never went into production, I love it, and feel it is important to retain the originality.

The head is off now, and it IS HGF, so really the best result I could hope for, I'm in agreement to stevieturbo's comment about final setting up on the road, this is what will be done after the new HG's are fitted. I did this with great results when I first got the car, and then had it proven on a RR.

Thanks for your replies,

Chris.

[stevieturbo]

Im not sure its fair to point fingers at a tuner, when having to work with very limited methods of tuning....and you just say it was a power run. Not a real tuning session.

Although....how good can their setup be, with crap fans. Its hardly worth having rollers, if you dont have good fans.

[ScoobieWRX]

3 things in the main determine if you car dets. AFR - Timing - Boost. There are lots of other issues to contend with that could contribute to det but in the main....
....Too lean and it dets
....Too much timing and it dets
....Too much boost and it dets.
....Too much of everything and it's hasta la vista engine!!

Get these three right and you will be not very far off. Personally i would start again, set everything to safe levels or factory standard/defaults and go from there.

You need some way of logging engine dynamics so my advice would be to get some proper logging software on a laptop, appropriate cable (is it OBDI or II?), and get logging. There is no substitute for on the road logging/tuning so you get real world results. The megasquirt sounds like a top idea and best way around your det issues!!

Good luck with that

[stevieturbo]

ScoobieWRX said:

3 things in the main determine if you car dets. AFR - Timing - Boost. There are lots of other issues to contend with that could contribute to det but in the main....
....Too lean and it dets
....Too much timing and it dets
....Too much boost and it dets.
....Too much of everything and it's hasta la vista engine!!

Get these three right and you will be not very far off. Personally i would start again, set everything to safe levels or factory standard/defaults and go from there.

You need some way of logging engine dynamics so my advice would be to get some proper logging software on a laptop, appropriate cable (is it OBDI or II?), and get logging. There is no substitute for on the road logging/tuning so you get real world results. The megasquirt sounds like a top idea and best way around your det issues!!

Good luck with that

The naivety of those who think you can simply plug a laptop into everything, just like that.

[Daveuk9xx]

You haven't said, or no one has asked, under what circumstances it dets on the road. Full throttle, part throttle, high rpm, low rpm? If you only had a power run on the rollers then it was have been at WOT all the time. You may well have sufficient part throttle ignition vacuum advance to be causing det at lower throttle openings but not at WOT. If so that's an easy fix.

Personally I can see no way that any car would det on the road but not on rollers at the same throttle and rpm positions.

Dave

[Munter]

Daveuk9xx said:

You haven't said, or no one has asked, under what circumstances it dets on the road. Full throttle, part throttle, high rpm, low rpm? If you only had a power run on the rollers then it was have been at WOT all the time. You may well have sufficient part throttle ignition vacuum advance to be causing det at lower throttle openings but not at WOT. If so that's an easy fix.

Personally I can see no way that any car would det on the road but not on rollers at the same throttle and rpm positions.

Dave

I think that might be because he found head gasket problems and is seeing if that fixes his problems 1st...

As for OBDI or OBDII.

[Daveuk9xx]

Munter said:

I think that might be because he found head gasket problems and is seeing if that fixes his problems 1st...

His head gasket problems are far more likely to be the result of the detonation than the other way round!

Dave

[ScoobieWRX]

stevieturbo said:

ScoobieWRX said:

3 things in the main determine if you car dets. AFR - Timing - Boost. There are lots of other issues to contend with that could contribute to det but in the main....
....Too lean and it dets
....Too much timing and it dets
....Too much boost and it dets.
....Too much of everything and it's hasta la vista engine!!

Get these three right and you will be not very far off. Personally i would start again, set everything to safe levels or factory standard/defaults and go from there.

You need some way of logging engine dynamics so my advice would be to get some proper logging software on a laptop, appropriate cable (is it OBDI or II?), and get logging. There is no substitute for on the road logging/tuning so you get real world results. The megasquirt sounds like a top idea and best way around your det issues!!

Good luck with that

The naivety of those who think you can simply plug a laptop into everything, just like that.

Yeah...really naive eh

I use a laptop for mapping and logging through my OBDII port...what's naive about that?? If you had a megasquirt you would do the same via it's serial interface and map or log using their proprietry software and something like logworks for logging, add to that an LC-1 or LM-1 wideband to check for AFR's and you're on the way. After 1996 most Euro,USA and Asian car manufacturers installed an OBDI or II interface to their cars for diagnostics purposes.

The OP's car is older than that and there will be other options for him but there's nothing naive about plugging laptops into cars.

I also said there would be a whole host of other contributing factors causing his det but without seeing the car and seeing what's it's doing it's difficult to give any kind of diagnosis.

Edited by ScoobieWRX on Monday 21st July 19:45

[Mr2Mike]

ScoobieWRX said:

[
Yeah...really naive eh

I use a laptop for mapping and logging through my OBDII port...what's naive about that??

I suspect the idea of finding an OBDII port on the pre-historic K-Jetronic (mechanically injected) system have given a couple of people a chuckle. Your car and your experience are from a different era in this case.

[taz turbo]

I can plug my laptop into the car but only with an inverter through the cigar lighter socket.

Seriously though, the HGF IS a result of the detonation, I'm not pointing the finger at the 'tuner' but do feel as the 'expert' on these engines, charging £150/Hour plus VAT, it possibly I should of left with some advice/recommendations.

I have said 'power runs' as, there were little changes made to the set up, a dizzy swing 2-3 degrees advance or retard showed an overall reduction in power, and emissions showed OK

The 'systems' used may be 25 years old but produced good reliable power for the last 18 years I've had the car, and the 7 years before that, so I don't see why it shouldn't continue.

As it was No.6 that has had the problems I suspect the problem is down to a lean(er) mixture on this cylinder. No6 (and 5) are within a couple of inches of the turbocharger and do run leaner than 1-4, at the advice of an Ex turbo technics engineer (similar installation) 'Run it richer than you would normally, not bore wash levels, just safe'

Thanks for your replies,

Chris.

[ScoobieWRX]

Different era....probably not as i go back quite a way. I used to run a Triumph 2.5pi and that had a mechanical injection system that was mechanically driven not just operated.

With all the greatest respect a Bosch K-Jetronic system is only mechanically operated but still relies on Air flow and fuel pressure just like elecronic fuel injection even though it runs all the time instead of pulsing, and uses a pressure valve instead of an electrically operated solenoid and electronic pump to squirt fuel.

Instead of altering fuel mixture electronically you have a grub screw that alters AFR but can still be measured using a wideband linked up to a laptop. You can still measure the airflow electronically by fitting an aftermarket MAF sensor before the Turbo inlet and hook that up to a laptop. You can take an analog output from the Motorcraft OEM ignition system and Micro Dynamics ignition controller with the appropriate interface and measure that on a laptop, same with the Turbo measuring boost with an electronic guage and controlling boost with an electronic boost controller, or you can even hook that up to a laptop, and if you want to keep and eye on Det get yourself a knock detector with an output that can be linked up to a laptop. Is that really altering the car very much??

There's very little on that cologne engine that cannot be measured using a laptop and a bit or todays tech. The only difference is how deep are the OP's pockets, and is using a bit of modern technology really going to make much difference to the originality of the car bearing in mind it already uses an aftermarket igitnion controller to pull timing or was that part of the original prototype car, and how far does the OP want to go to get things right??

There's nothing niaive about using todays technology on classic engines to help you along the way. It's normally not a permanent install and you can always uninstall it all afterwards to keep it as original as you'd like once you've done the deed. In fact i think it's probably a bit niaive not thinking of doing it that way in the first place.

No doubt we'll agree to disagree on this one.

[Daveuk9xx]

taz turbo said:

As it was No.6 that has had the problems I suspect the problem is down to a lean(er) mixture on this cylinder. No6 (and 5) are within a couple of inches of the turbocharger and do run leaner than 1-4, at the advice of an Ex turbo technics engineer (similar installation) 'Run it richer than you would normally, not bore wash levels, just safe'

Thanks for your replies,

Chris.

I remember doing flow development work on the 2.8 V6 heads and manifolds many years ago and the inlet manifold was exceedingly grim on some cylinders. Actually it was grim on all cylinders but much worse on some than others. I forget the numbers now, it was nearly 20 years ago, but the manifold was knocking off 20% or more from the bare cylinder head port flow.

Getting big inlet valves to flow properly was another PITA with every port in each head actually being a different shape with a different amount of bend to it.

Dave

[Mr2Mike]

ScoobieWRX said:

Different era....probably not as i go back quite a way. I used to run a Triumph 2.5pi and that had a mechanical injection system that was mechanically driven not just operated.

With all the greatest respect a Bosch K-Jetronic system is only mechanically operated but still relies on Air flow and fuel pressure just like elecronic fuel injection even though it runs all the time instead of pulsing, and uses a pressure valve instead of an electrically operated solenoid and electronic pump to squirt fuel.

Since you appear to have some understanding of how the K-Jetronic works, why would you think it had an OBDII port?

[ScoobieWRX]

Mr2Mike said:

ScoobieWRX said:

Different era....probably not as i go back quite a way. I used to run a Triumph 2.5pi and that had a mechanical injection system that was mechanically driven not just operated.

With all the greatest respect a Bosch K-Jetronic system is only mechanically operated but still relies on Air flow and fuel pressure just like elecronic fuel injection even though it runs all the time instead of pulsing, and uses a pressure valve instead of an electrically operated solenoid and electronic pump to squirt fuel.

Since you appear to have some understanding of how the K-Jetronic works, why would you think it had an OBDII port?

When the OP wrote 2.8 Cologne i immediately thought of the Ford Scorpio and Capri that had a diagnostic serial port (EEC/IV and OBDI type), i didn't realise it was a TVR he was talking about. I know they used Cologne engines in the 280i, Tasmin and S series, and the 2.9 Cologne's as well but apart from that i know little about TVR's.

I had a couple of old 240 GL Volvo's too and they had K-Jetronic fuel inj.

[Daveuk9xx]

ScoobieWRX said:

When the OP wrote 2.8 Cologne i immediately thought of the Ford Scorpio and Capri that had a diagnostic serial port (EEC/IV and OBDI type), i didn't realise it was a TVR he was talking about. I know they used Cologne engines in the 280i, Tasmin and S series, and the 2.9 Cologne's as well but apart from that i know little about TVR's.

I had a couple of old 240 GL Volvo's too and they had K-Jetronic fuel inj.

Whether it's a TVR or not is irrelevant because no Bosch K system ever had an OBD port because it's not an electronic fuel injection system. You can wriggle all you like but you'll only dig a deeper hole.

Dave

[ScoobieWRX]

Sorry, you're absolutely right.

It was 1986 that Ford replaced K-Jetronic with L-Jetronic controlled by EEC-IV ECU on the 2.8 for a year moving it to the 2.9L and thereafter replaced by the 2.4L

My mistake