Somebody sent me an email yesterday, they have a Superformance S1 running with a Zetec and quad throttle bodies, using a Pectel in Alpha N mode. Superformance doesn't know how to tune the Pectel, and he was bringing it to another tuner. He wanted some advice on tuning the Pectel, and I ended up writing a huge thing again. It has a lot of good info, and I wanted to share here.
I'll take questions if anybody wants to ask some tough questions, but please don't ask things like "what's a Pectel".
I'll take questions if anybody wants to ask some tough questions, but please don't ask things like "what's a Pectel".
Well, looks like you've got a big job ahead of you.
Who have you been working with at Pectel? The guys in California? I have to caution you, that myself and others have found they really don't know as much as you would think dealers should. I had a problem with my basic Zetec Turbo setup, for which they claimed the T2 was a "plug and play" setup. I had tuning issues, and they couldn't even begin to help me out. I ended up contacting Pectel in the UK, and it turns out I uncovered some problems with the software. I believe I was the first one to even try to use the two "modules". It's been about 10 months now, and still no fix. The modules aren't likely to be causing your problem, and you can run with them disabled, as most people are. That's what I'm doing now as I await a fix.
As for RPM-motor-sports, who referred you to them? I looked at the web page, and didn't really see anything that impressed me. Do you know somebody that has used them? I mean, maybe they are good, but I don't really see any customer cars that show they know how to tune an engine, or anything like that.
There are a lot of shops out there that really don't know how to tune engines. They usually manage to get them running well enough to get down the 1/4 mile at full throttle, but really don't know enough to make a car run right at part throttle and different weather conditions. When I first got my system, I went to XXXXXXX XXXXXXXXXX, and paid $300 for about 2 hours of dyno time. When I left, my car ran worse than when I brought it in, and actually would have died if I'd kept using their map.
I did a lot of tuning myself on the road with just the narrowband O2, and just my wits. It worked out well, part throttle drivability was much better than the dyno tune. But I knew that I had no clue about full throttle mixture. It's easy to get the part throttle stuff with a narrowband, because you're shooting for 14.7:1 anyway, which narrowbands are very good at indicating. But at full power, you need to know the actual A/F.
I ended up buying myself a Motec wideband O2, and finishing my mapping like that. It was pricey, but I figured a couple hours on the dyno and it's paid for itself. I like tuning on the road better than the dyno, because it REALLY simulates real road loads, airflow, engine temps, etc... But in a fast car, it can get pretty hairy. You basically have to drive down the road, holding the car from accelerating with the brakes. With a powerful car, it's a bit un-nerving.
The real KEY to tuning A/F, is you have to take the car to EVERY load site, and tune that A/F. Every single site. It's actually not that bad, takes about an hour. This CAN be done on a dyno, but NOT a Dynojet. A dynojet lets the engine accelerate slowly, holding it back with the weight of the rollers. But it's ALWAYS accelerating. What you need is to hold it at one rpm, control the throttle to hit a load site, and tune that site, move up to the next load site, tune it, move on... until you are done a column of loads @ one rpm. Then you move to the next rpm column, and do all the loads. You can't do this on a Dynojet. What most tuners do, is floor the car, let it accelerate to max rpm. Look at the A/F trace, and then fiddle with the settings. Run it again, over and over. It's just not efficient. Something like a Mustang dyno can hold the engine at a given rpm, and let you stay in a cell until you get the A/F right. You can also do this on the street using the brakes as I mentioned.
The other problem with most shops, is that they don't have a good understanding of the physics involved with air density changes from temperature and pressure. That's what the guy I went to really screwed up. He didn't have a clear understanding of the effects of air temperature. The car ran okay in his hot dyno room, but soon as I took it out into the cool air, it was pretty ugly. What I ended up doing was just inputing corrections for air pressure and density that are based on the physical models of air.
Now, what about timing? Well, you have to start somewhere, and in my case I'm still running on "best guess" timing. I have a good ear for detonation, and haven't had any problems. But I'm probably not getting as much power as I could. Eventually I'm going to go to a Mustang Dyno, and tune the timing. It's the same deal as the A/F. Most tuners just run it up at full power, and tune the top power timing. What you need to do, is hold it at each [email protected] cell, and play with the timing until the dyno shows maximum power. You really can't do this on the road, because it's basically impossible to feel small differences in power.
I think the reason so many dyno tuners around here don't know what they're doing is because most of the time, they're tuning drag cars. All they have to do is get the car to start, idle, and then launch at full power and down the track they go. I don't think that's what you want, so you really have to watch what you do, who does your tuning.
Another thing is, a lot of these guys mostly tune chips for factory computers. In most cases, the factory part throttle tune is already good, all the air temp factors are well accounted for, and all they have to do is modify the full power settings. A lot of them just really don't know how to tune an engine from scratch, which is what you need with the Pectel.
I've never found any really good books on tuning. There is one that's decent, written by Dave Walker who is a tech editor for Car and Car Conversions magazing in the UK. You might know that magazine, if you're a fan of Caterham type cars, since it's full of cars just like that. The book is called Engine Management: Optimizing Carburettors, Fuel Injection and Ignition Systems and it's available at Amazon.com if you're interested in reading up. It's not quite a "step by step guide", but it's a really good primer. From there, you really need an understanding of the physics of air, because he doesn't get into that as much as I'd like.
I actually learned most of what I know now, from reading Ford training manuals for engine calibration engineers. It's really a shame they don't publish them, because it's the best source I've found, by far. It's interesting, because inside the factory computers, it's basically running on a physical model of air. You can actually get the engines running pretty well in most cases just by inputting some information on the engine, and some tables like Airflow Meter Calibrations, and it does the rest. It would just need fine tuning from there. It's just interesting that you could run an engine purely based on accurate phsyical models of air.
That pretty much confirmed what I had done to get my car running, by using some of the laws to fill in the tables like air temp correction, etc.
The air temp and water temp sensors I'm using are the ones they sent with the T2 Focus plug'n'play kit. I'm not sure exactly which they are, but I'd think you had the same ones. What is the problem with the ones you're using?
So, I really don't have much info I can pass on to those tuners, I'm basically more concerned with warning you to watch what they're doing. In my case, I didn't know much when I went to the dyno, and the guy was a shyster. He BS'ed me to keep me on his dyno. When the car didn't run right after, he blamed it all on me. The fact is, my car was detonating HEAVILY when I left his shop and would have blown if I kept running it, I fixed it just by putting the accurate physical models back in. I've been running now for almost a year, 9psi boost on a stock block and internals, all through the winter, summmer, and about 300 miles on a road course so far. The car starts and runs well, idles better than stock (I'm the only one I've found to actually use the closed loop idle). I'm also getting around 26mpg, which I find is a good indication also, of how well the engine is running. If you're using stupid amounts of gas, it's not running right.
The only real info I could pass on to those guys is the two modules which do not work. The first is closed loop narrowband oxygen sensor feedback. It has an error where sometimes it defaults to minus 100% fuel. It's kind of an intermittent thing. Pectel has admitted to a software error, but have not fixed it yet. You have to watch the values of the Lambda correction. When it enters closed loop mode, it should start at 0% correction, and slowly adjust whichever way it needs to go to hit 14.7:1. When the error occurs, it starts at -100%, pulls 50% of the fuel, and the car barely runs. It knows it's lean, and it starts adjusting up but it takes a long time to get close to 0%. There's really nothing you can do, if it is giving you this problem, just disable the feature. I doubt it's an issue for you, since I doubt you're running O2 sensors.
The second feature which doesn't work is Decel Fuel Cutoff. The idea is, when you're coasting down in a gear, it turns the injectors right off. Most stock cars do this, it saves fuel. The problem is when you step on the gas and the fuel comes back on, it has a period where it needs to inject more than the necessary fuel to get the manifold walls wet.
Intake manifolds always have "puddles" of fuel which stick to them, right under the injector. In normal circumstances, the fuel is being sucked off the puddle as fast as it is being added by the injector. Anytime you quickly change the fueling however, the puddle needs to chance size. This is why you used to have throttle pumps on carbs. It's also the reason for the "Transient Fuel" correction in the Pectel. When you step on the gas, and the injectors spray more fuel, the puddle grows. There is a delay in the fuel that the engine gets, as the puddle grows to the new size. That's why you inject more fuel for a split second when you step on the gas. That's transient fuel correction, it overfuels the motor, so that it gets the right fuel as the puddle grows (this all takes split seconds).
Anyway, back to decel fuel cuttoff.... The cuttoff works fine, it shuts the injectors off. The problem is when you get back on the gas, it does a period of overfueling, to grow that puddle again. The software error makes the overfuel correction stick. It just gets stuck on, and the Pectel overfuels the motor.
Same deal, Pectel hasn't fixed the software yet, and there's nothing you can do. Just turn the feature off, disable it. Both of these two errors are not seen by most people, because they just aren't using them anyway. As far as I know, I'm the first to try, and I discovered the problem.
One thing you need to ask these guys, is have they ever tuned an "Alpha-N" system. That's what you've got. Throttle bodies, with no MAP sensor. It's the trickiest system of all, Mass Air is the easiest, then Speed Density which I'm running, then Alpha N. If they don't know what you're talking about, they probably won't be successful tuning it.
The last thing I want to say is, that I'm trying to get started in the tuning business. I don't have a dyno, but I do a pretty good job despite that. If you're interested, I can help tune your car before, during, or after you visit these guys. If they leave you with a car that only runs well at full throttle, you need my help. If you're interested, let me know.