Chips wiv dat plees (S2 Promax chip)

[poprock]

That’s a really good read Oli. Thanks for making the effort to write it up. Not so relevant to those of us with the (naturally much faster) Turbo cars, but fascinating nonetheless.

 

[barks944]

I expect the ignition maps will have been extensively modified. I don't think our DME's are clever enough to continuously optimise ignition using the knock sensor they simply heavily retard ignition when they detect knock, I think at least on the turbos this is how it works. AFR's probably havent changed a great deal so its probably mostly ignition thats giving the improvement.

 

[chrisg]

Oli I'd echo the sentiments of others - a great write up and thanks for taking the time to post this. I'm intrigued by your comment "it eats 951's for breakfast...." I'd be interested to see how you got on against my 951 with a Promax chip, oh and a rebuilt blue-printed engine........ Not that, that's a challenge....

 

[zcacogp]

OK, this is a post (or thread) which I have owed Andrew Sweetenham (Promax) for some time. Some of you will recall a thread a while ago which talked about chips for normally-aspirated 944's and particularly the S2. Without wanting to go over old ground, Andrew Sweetenham very kindly provided me with a chip for my S2 for evaluation purposes, on the basis that I could fit it and pay for it as and when I was happy with it. As it was, I insisted on paying for it before fitting it, but greatly appreciated the trust shown - thank you Andrew.

The car is an '89 S2, 155k miles on the clock, full service history, owned by me for the last 3 1/2 years, during which time I have done 40k miles in it. Largely standard, but with some holes cut in the airbox to improve breathing. (A mod I'm not sure I would recommend, before anyone asks.) Last time it was on a dyno (Weltmeister) it pushed the needle to 220bhp, which suggests that it's in half-decent nick. It's always run on higher-octane fuel, for reasons disussed elsewhere on here (it runs more smoothly and gives better MPG - which more than compensates for the extra cost of the fuel.)

The chip is the standard S2 chip from Promax. £100 including post and packaging (and a nice note asking that I let them know how I get on!) As with all S2's my car eats 951's for breakfast ([]), but I was intrigued by the notion of yet more power, particularly in the mid-range. The Promax chip generally gets a good write-up on this forum, so I thought I'd give it a go.

Fitting

Fitting it is a fiddle. It's actually quite difficult. Getting the ECU out is easy (passenger footwell), opening the ECU case takes a bit of brutality but isn't hard. However, for the S2 (and possibly other models), you then find there are two PCB's, one above the other, and you need to seperate them to get to the chip. Unclipping the back of the top board is a cinch, but the front is a part of the socket on the front of the assembly, and you need to flex the socket quite a lot to unplug the board (and the instructions don't make this clear). This takes more force than I was comfortable with (given you are working with PCB's), but it did come apart in the end. Removing the old chip and replacing it with the new one was very easy, and re-assembly was much easier than dismantling.

Starting

The chip is good. But it does have it's downsides, and one of them seems to be the starting. I think that the car is harder to start with the Promax chip fitted. It seems to spin for longer before catching; something I noticed immediately. I'd be interested in hearing whether this is just my impression or whether other S2 owners have found the same when fitting this chip.

Cold driving

Another downside: fuelling when cold. Particularly when coming off the throttle, when slowing down or changing gear. A close analysis of the fuelling maps would confirm this, but it feels very much as if the map in the Promax chip is rather quicker to shut off the fuel than when using the standard chip, and it makes the car very difficult to drive smoothly when cold. It's not much of a problem, but it's not just me; Mrs zcacogp noticed it immediately and commented on it. Once the car is warmed up the problem seems to go away (or it gets easier to drive around).

Hot driving

OK, I said the chip had some downsides. But it has some pretty good upsides as well. And that is the mid-range torque; I don't have any dyno plots to give figures, but it is significantly more beefy anywhere above about 1500rpm. It makes the engine feel 'bigger'; more like the 3 litres it claims to have. Everyday driving is easier as it will pull more smartly from a given speed in a high gear. Cruising 'round town is done in 4th and 5th instead of 3rd and 4th. And if you are feeling lairy, a quick change down to 2nd will break rear-end traction very readily on corners, with all the usual associated fun. [] The smoothness of the power delivery makes such irresponsible behaviour easy to explore and easy to control, but is surely only the behaviour of chavs and hooligans and therefore not the sort of thing you'd ever catch me doing!

The S2 always comes on cam at about 4k rpm, and while this characteristic isn't lost, it's not as obvious with the new chip. There is a step in power at 4k, but it's smaller. As 4k rpm in 5th equates to about 100mph, with the standard chip the car always seemed to accelerate more briskly from 100mph than from 85 or 90mph. The new chip, with a smaller step in the middle of the power band, makes high-speed cruising more relaxed; you can pootle along at 80-90mph without feeling any lack of urge on tap. This is a definite asset for motorway driving.

Of course, more mid-range also means that if you don't put your Captain Sensible underwear on, the car is quicker. And it feels quite a lot quicker - no doubt about that. From a standing start, it pulls more willingly, more enthusiastically through the rev range, and you can certainly notice that without a dyno to give you numbers. A good spank along an open road reveals a more lively power delivery, and as a result the car is more fun to drive. More power in the mid-range seems to encourage me to drive it harder (naughty!), but not into such high rev ranges. With the old chip, I would not-uncommonly clip the rev limiter when really pushing on, but the power delivery characteristics with the new chip seem to encourage me to change up a smidge earlier - as a result, I haven't found the rev limiter since it was fitted. (Re-reading that, it does occur to me that this could be because the new chip has changed - or removed - the rev limiter; can anyone confirm whether this is or isn't the case?)

So, a couple of minor downsides, and a thumping great big upside. Any other comments?

Well, yes actually. The car in question is normally aspirated, so pretty much the only changes that can be made by the ECU are to the fuelling and the ignition timing. Ignition timing is (as I understand it) largely controlled by the knock sensor, which leaves only fuelling. So, more power would expect to come at the price of lower MPG - non? Well, in the absence of enough testing to give reliable figures (I can't have done more than 500 miles since fitting a month or so ago) it seems promising. A long run from London to Shropshire and back suggested that the MPG is slightly improved on the old chip. Which, in these days of stupidly high fuel prices would be very nice.

Having said that, I serviced the car soon after fitting the chip and discovered that the plugs were very sooty. Dry, but lots of carbon. I know the car runs a smidge rich (it had high CO2 at the last MOT), but the soot on the plugs was enough to raise an eyebrow. The car had been used for a number of short journeys 'round town shortly before the service, and this would have contributed significantly to the sootyness. What I'd like to do is a find a gas tester, and see what gasses are being produced by the engine at a variety of engine speeds, once warm. Ideally, I'll do the test twice - once with the old chip and once with the new chip, and see what the differences are. I'll report back once I've done this, with some results - maybe later on this summer.

So, the chip. An improvement? Yes. Worth £100? Yes, I think so. I'd recommend it, for sure. And on that note, you'll have to excuse me; I think I have a couple of 951's caught in the air filter and need to go and clean them out ... []


Oli.

 

[MRGT]

Good write up Oli I too very recently fitted a Promax chip to my 'S', whilst obviously not as quick and meaty as Oli's S2 [] it definately has a bit more 'whoosh' to it (well, as much 'whoosh' as an S will ever produce [] ) However unlike Oli I have found no downside at all, she still starts and runs from cold just fine. The only thing still to check is mpg but as I have only covered approx 100 miles since fitting its too early to tell ( The S is well known for responding to high revs and now seems to want it to even more [] ). I am planing to visit Allan Jeffries in Plymouth sometime in May to run back to back rolling road runs, so will report back then. Howard

 

[zcacogp]

Chaps, Re-reading the review, it probably sounds a bit more negative than it should. Andrew told me that he tells customers that if they drive around with the new chip for a while, and decide later on that it's not worth it, he will refund the money if they return it. I can't imagine he gets many returned ... it's well worth while. I also didn't say that the benefits are all mid-range. OK, maybe not all, but I don't think there is anything much at all extra at the top. It is very much a mid-range affair. Although that's not to knock it; very little of the time are you driving flat out, and mid-range is what makes a car drivable. More of it is a good thing. Howard, interesting to hear your comments about the chip in your S. Glad you are getting on OK with it. Let us know what the dyno figures reveal.

ORIGINAL: chrisg I'm intrigued by your comment "it eats 951's for breakfast...." I'd be interested to see how you got on against my 951 with a Promax chip, oh and a rebuilt blue-printed engine........

Oh, that was you I went past on Friday morning? Up near Cambridge - non? Looked like you had it jammed in reverse - hope everything is OK. I really should have stopped to help out. (Or was that just the relative difference in performance between a 951 and a mighty S2!) [][][] Oli. (No offence meant ChrisG!)

 

[morris944s2john]

Thanks for the good write up! Do you have any plans to put the car back on the dyno post chip fitting??

 

[zcacogp]

ORIGINAL: morris944s2john Do you have any plans to put the car back on the dyno post chip fitting??

Thanks John, No, no plans. Partially because it would gain me nothing (I don't much care how many BHP it has, although a comparison of the before and after curves would be interesting.) However the last time it was on rollers was a couple of years ago, so in order to get a meaningful 'before' and 'after' I'd need to do it again with the old chip and then with the new one, on the same rollers, within half an hour or so of each other. All of which would be time-consuming and expensive. If someone else wanted to pay for it for research purposes then I'd happily allow my car to be used tho'. Oli.

 

[pauljmcnulty]

Thanks for the good write up! Do you have any plans to put the car back on the dyno post chip fitting??

Indeed, great effort. I don't like the idea of dynoing as part of discussing a chip, personally. Promax always insist that theirs isn't meant to be a chip that raises power, but that it smooths out power and torque making the car more driveable. I suspect that the purely academic figures achieved on a dyno wouldn't have much relevance. In fact, I think it could even be detrimental. Suppose chip A produces an extra 5BHP, there will soon be someone who markets a chip B with 10BHP, regardless of the other, more useful, benefits like smooth power and reliability. Headline figures do sell, witness the current trend for cars that have to beat rival's times around the 'Ring, leading to setups that are compromised on UK roads.

 

[MRGT]

Paul I agree that max BHP is a bit meaningless, the reason I am choosing to do back to back runs is to look at the output over the whole of both the torque and power curves. After fitting Promax's chip my 'bum dyno' definately suggests a big improvement in overall drivability especially between 3000 and 5000 rpm, and so to satisfy my own curiosity it would be nice to see it down on paper. Given that the 'S' doesnt achive max BHP until 6000RPM I would happily see a lower max BHP at that figure if it provided more a better bhp/torque curve lower down the range Howard

 

[pauljmcnulty]

Given that the 'S' doesnt achive max BHP until 6000RPM I would happily see a lower max BHP at that figure if it provided more a better bhp/torque curve lower down the range

Get yourself an S2, then! [][] Good point about the torque spread being shown on a dyno graph though, it'll be very interesting to see.

 

[MRGT]

ORIGINAL: pauljmcnulty Get yourself an S2, then! [][]

And suffer from rusty sills ? I dont think so [] In all honesty for the budget I set aside 18months ago for a 944, S2's were out of reach, if I was buying now with the same budget they would be within budget, such have prices dropped. []

 

[pauljmcnulty]

In all honesty for the budget I set aside 18months ago for a 944, S2's were out of reach, if I was buying now with the same budget they would be within budget, such have prices dropped.

It is sobering. My S2 cost less than my Lux, five years earlier. I thought a Lux, in good nick, wouldn't drop far below the £4K mark over time, yet I still say the same thing about my S2! [&:]

 

[Diver944]

Nice write up Oli and glad to hear you're happy with the results. If anyone wanted to see Dyno graphs for chipped and standard S2's then simply take a look at Ricks website, the top 10 normally aspirated cars are all S2's (or have S2 engines) http://www.cannell.co.uk/944%20UK%20League.htm Ignore the peak power figures, but if you look at the shape of the curve further down the rev range it's easy to see that the chipped ones make their power and torque earlier and lower down, therefore increasing the drivability and mid range 'shove'

 

[Copperman05]

Good read Oli! The promax chip (and possibly other chips) is probably one of the few perfornace mods available for our S2's so its good to know they do work and are worth the £100 most of us are willing to invest in improvements. I too had the Promax chip fitted last year and I agree withl your findings, it definately has increased mid range and the engine feels significantly more eager. I also just happen to have had my car dyno'd both before and after the chip was fitted (both on the same branded machine but at different companies), interestingly it showed a peak increase of about 8hp and 15ftlb torque compared to the standard ship, but really shined in the mid-range showing 10hp and 20ftlb torque which translates into something quite noticable on the road. Personnaly I havent noticed any longer starting times or issues with cold running with my S2, I agree it can be a tricky thing to fit, although now I've done it doing it again would be quite simple... Edd

 

[MarkK]

Great post,really enjoyed it,makes me want an S2 with a Promax chip,must say I had a spin to Rutland water in an S2 courtesy of mr Smith and was well impressed big low down smooooth grunt.Will get one at some point hopefully.A good read!!!

 

[evoboy69]

Very interesting to hear your findings but the difference sounds a little too subtle to me…

 

[zcacogp]

ORIGINAL: evoboy69 Very interesting to hear your findings but the difference sounds a little too subtle to me…

It isn't night and day in terms of outright power, but 'subtle' is underplaying it. The difference in mid-range drivability is significant. It's £100 well spent in my book. Oli.

 

[Copperman05]

ORIGINAL: evoboy69 Very interesting to hear your findings but the difference sounds a little too subtle to me…

The differences may sound sutble but you need to look at is like this, if the stock chip produced say 100ftlb torque at a given rev range and the promax chip gives 120ftlb at the same revs then thats a 20% increase in torque over the stock chip (I think), yes at peak power the effect is subtle as the increase is clouded by the overall output at that rev range, but in the mid range and even the lower midrange the difference is noticable as the difference is more marked compared to the standard chip. If that makes sense? Edd

 

[Hilux]

Great write up, great effort.................................however you still have a few issues........... One assumes the timing is correct, the cold start sensing is correct, the fuelling is correct, the spark intensity is correct, the compressions are ok and the injectors are clean and spraying properly. Tuning is like a suspension system, its the sum of the parts as a whole that make the difference.