94 Formula

Anybody have any tips or links to information on partial throttle tuning. Fueling is easy enough, but what do you look for when changing timing?

GuitsBoy

iTrader: (4)

Unfortuneately without a variable load dyno, its not really possible to tune this in perfectly. I just started with a stock timing curve that i liked, and added a few degrees across the board. Then I set my idle and WOT zones to what I wanted. Then i added some more timing to the off idle area to combat bucking. Any place I got any KR I just removed a degree or two.

ringram

Yeah its an art form. Take a look at some stock tunes and as Guits says start there and work forward.
I think I can kind of tell then things are running well. The engine sounds more angry and leads the throttle. When timing is out, it lags the throttle and sounds muted. You can check against KR, but the best thing is to try different base tunes. You will soon "feel" when it is running better. Might not feel any faster but will appear to the ear as more aggressive.

RedWS6 00

I'm just about to tune the timing on mine and have a question.
When looking at timing and you see knock retard do you assume its going to be reading from the low octane table? I will be using high octaine fuel in a few months, just tuning for the lower octaine, which is rated at 95 RON, hopeing I can tune the low octane table for the cheaper stuff, and then work on the high octane table later this year. So my question is, if the knock sensors detect knock does the PCM start using the low octane table?

SSpdDmon

iTrader: (10)

Copy high spark to low spark and then you don't have to worry about which table is being used. Just keep an eye out for knock. When you have the table you want, load a stock file to compare your tune against. Restore the stock low octane table and add in the difference between the current high and stock high table. This will restore the OEM range between the low octane and high octane tables.

ringram

Well, Id leave low octane as a failsafe, always tune for high octane, low octane you can just take say 5 deg off high. With no sustained KR or failed sensors the tune will always stay in high. You should not use low octane as its name suggests to tune that table for low octane as irrespective it will always try high first and once its knocked it will return to high and knock again. Bad idea. Tune the high octane for the fuel you use and stick with that fuel all year around. You can use the IAT and ECT spark modifiers to adjust for summer and winter temps.

GuitsBoy

iTrader: (4)

But then again, if youre running SD and you dont have teh 1 bar OS update, youll default to the low octane table, so you should copy the high over the low table for tuning purposes anyway. As long as you dont have persistant knock, youll do fine.

jimmyblue

iTrader: (11)

The way I did mine, was just to drive and log it;
after each time I would pull up the spark retard
histogram, max view (HPTuners) and where I saw
retard took out two degrees while where I saw
none, added one. This all won't work well unless
you settle down the KR attack/decay but if you
do it will make the actual knock-point more clear.
Enough of this and I had a timing table and a
resulting log histogram where I hit 1 degree of KR
in almost every cell. Subtract 3 degrees across
the map and there you are, right on MBT. Then
past it to the LO table and take out another 4
there for bad gas and bad weather.

RedWS6 00

Thanks Jimmy, I'll give it ago.

I'm going to start using the high octane gas soon, only 1 in 5 gas stations does the one I want, its 99.9 pence per litre = $8.16 dollars per gallon. The cheaper stuff I use is only about $0.60 per galon cheaper, so its not a lot of difference. I'm not complaining about cost as having this car is well worth it.

Soon I'll get this knock retard under control. Got the AFR pretty spot on across the board. I should have sorted out the knock retard before, nearly alays get knock above 4000rpm, took out a few degrees today and got no knock.

ringram

Hey Red you need a cam to help eat all that spare injector capacity!

RedWS6 00

Yes I do, I got the injectors ready for future mods. Am keen on the Magic Stick 4, but then should I save more and change heads too. Then if I'm going to do that and I want to go forced induction later do I choose the heads best for FI, and the list goes on. I cant really afford forced induction yet, nor heads for that matter, but can afford a cam with the gasket set, and pushrods, I guess I should invest in some decent rockers too. I'm hoping I'm pushing 350+bhp, no local dynos here to test on, there isn't much in the way of competition in the area, a couple of Mitsubushi EVO's, and Subaru's, most cars are small here and low powered, however I still want to mod my car further as I just like the feeling of power..... dont we all. :O)

I contacted Texas speed about getting a cam shipped to England, but no response yet. I'll give it another go. I and still learning about cams, and in comparison the MS4 looks great, almost too good to be true. Still retains some power fairly low down in the RPM.

SSpdDmon

iTrader: (10)

Your car came with 350 brake hosrespower (aka hp at the crank) stock. They're under rated at the 320hp GM said they had. Now, rwhp is a different story. I'm guessing that's what you meant...

RedWS6 00

I thought they were about 320bhp stock, I done a few mods, exhaust, intake etc, both claim they add about 20bhp each, probaly a sales hyp., but then as my engine is 122,000 miles old, I'm probably loosing some power, who knows. I have a G-Tech, which measures power it at the wheels, but of course you have to take into account drag. Says I'm 290bhp and 304 ft/lbs at the wheels, and 349/365 at the crank (using an excel formula). The gas I'm using isn't top grade, so have a little knock about 4K right now, next tank will be some decent gas.

This MS4 cam claims to add 80hp, now that sounds great, just hope it passes the emmisions sniffer test. If my AFR stays between 13.6 and 15.6 during the test then it passes, they looks for a couple of other gasses to, I'm hoping all will e fine, its quite a relaxed emmisions test, I choose the RPM that they test at so we can get it through the test. :O)

GuitsBoy

iTrader: (4)

That is a monsterous cam. If youre emissions testing is anything like the states, theres no way in hell its gonna pass.

ringram

Hey Red, Im in the UK too you know, Im in London.. There are a few dyno's about that can handle it. One hub based one in Surrey looks good. abbeymotorsports I think.

I agree with Guits a big cam will fail. AFR has to read 15:1 to 14.4:1 at all test points. Overlap might mess with that too much. Also CO and HC emissions are checked. I dont think its too strenuous, but Ive not seen a definitive answer as to what cam will pass. Im running a 220/224 just in case. If I knew it would pass Id be using an F13 or big lift 224/228 for sure.

RedWS6 00

I havn't looked at how easy it is to change the cam, some people say you insert some rods to hold something up, pull out the cam and slide in the new and pull out the rods. All done in a matter of hours. If it only takes an evening and if it fails the test I could swap the cam to the stock one, pass the test and swap it back. I put the cats on just for the test, then take them off again after. The cam may pass the emmisions test here anyhow. The cats may clean it up enougth, after all the cats only do about 10miles per year.

I havn't found the cam numbers for the MS4, but the MS3 is 237/242. I am aware the higher the numbers the worse it is for emmisions. Why?, okay it seems like a newb question, but okay, there will probably be overlap when both valves are open at the same time, why would this cause problem with burning the fuel. As emmsions are measureing if the fuel is burt properly, and not too much air or fuel in the gases too. The idle will be lumpy, which is what I am after, but if I tuned it and ran the emmisoins test at say 2000rpm surely its possible to get it through. To get more power from the engine, which the cam does, is to make your engine more efficient, making more power from the fuel and air you are putting in, okay the cam is letting in more air, therefore you dump in more fuel. I'm know it does/can cause a problem with emmisions, I just wondered if there is an explaination.

Sorry, I ran away with someone's thread.

RedWS6 00

Hi Ringram, Good to hear from someone also in England. We have problably met at a show some time in the past, did you go to Wheelsday in Aldershot?
I'll have a look for abbeymotorsports.

On my last MOT I thought it said the Lambda had to be between .9 and 1.1 lamda. Thats 13.15 - 16.00 AFR, I could be wrong, I'll check my certificate again. It may have been 0.95 and 1.05 that would make 13.89 - 15.35, still a good range to hit. But as you say the CO and HC have to be good, last time I was at least 10 times under the limit on these two.

technical

That's the strangest emissions test I've ever heard. You can get a cam as big as a magic stick to run at 14.63, but it will most definitely create "non passing" emissions...at least they way we test them.

ringram

From memory CO must be below 3% and HC less than 2500ppm and Lambda within the range. Im pretty sure its 0.97 to 1.03 depending on what year you have.
Yeah I guess it stops you running lean to pass and upping NOx emissions.

RedWS6 00

Yeah, I think your right with the 3% either way of lambda.
The gas limit is around CO<=0.3%, HC<=200ppm
I remember i was 20ppm on HC and 0.01% on CO last year.
I wonder what cam I can get away with. I like to be dareing, I wouldn't mind trying a 224/228 and a nice lumpy idle too.