Welcome to the next installment of the

Topic of the Week
to run from 3/29/02 to 4/5/02

The subject for the week is all about tuning up the good ol' TBI.

Some suggested points of discussion:
- Ignition upgrades
- How to set timing with a timing gun
- How to set timing for best results
- How to use use external devices like scanners and WinALDL to aid in tune-ups
- Track improvements from different timing settings
- Milage gains from MSD or other multiple spark discharge boxes
- Best spark plug. Are the most expensive ones worth it?
-


Lets see lots of pictures and track improvements this week. =)

 

I am wanting to go with a .045 spark gap. I was thinking of using a MSD blaster coil to boost spark. Am I on the right track?

 

Yes you are.....there's really no point of getting a spark plug gapped to .045 over unless you're applying more juice. I highly recommend the MSD Blaster GM Coil (8226 @ $39) and the Hypertech Power Cap and Rotor (4060 @ $22) w/ AC Delco Rapidfire plugs w/ the .045 gap. I noticed a dramatic increase in throttle response and gas milage.

Now some would suggest using the MSD cap and rotor, but when I called MSD up about it, they actually suggested not using it, because it doesn't sit perfectly. I know some on here would beg to differ, but that came straight from the horse's mouth.

As far as wires are concerned, I went w/ MSD 8.5mm Super Conductor wires w/ 90* boots (31419 @ $59), because I plan on putting headers on later. They should arrive today, but I've used them on other cars, and they are the best in my opinion.

If you want to go with the sleeper look, I suggest using Hypertech components all the way around w/ Taylor wires. Hypertech parts are all black just like the originals except for a sticker on the coil I think. Taylor makes a good wire as well, and you can get them in different colors I believe.

 

One thing i can say is winaldl is key... It makes tuning so much easier when you can see what the ecm is doing. I like it so much i hardwired the circutry in my dash and installed a serial port in my trim beisle next to my climate controlls. Makes doing diagnostics a snap. Just plug the sirial cable in and off you go.

As for spark plugs i stick w/ the bosch platinums (not plus fours). Theyre around a dollar and change
a piece and ive been using them in all my cars w/o any problems.

Another often overlooked thing is the starter. No one i know ever thinks of maintaining all the connections and not letting them get corroded. The starter turns much faster w/ all the connections cleaned and maintained. It makes those cold starts a breeze.

 

A note about Platinum plugs, if you decide to go with an MSD ignition or something, platnium plugs will not work. This is what I have been told a few times. Most people suggest regular AC Delco plugs.

 

I need some info on TPS voltage and what it does. And what is MAP?

 

Last tuneup I used AC rapidfires, accel 8mm wires, and AC cap/roter. I dont think I'll use the rapidfires again, though. They were OK, but nothing to write home about. Ill just but the normal AC Delcos for $.89 or whatever they cost.

Also have the MSD Blaster coil. That did help out. Didnt do anything performance wise, but it really smoothed out my idle when I was stopped. The car would sputter a little at lights and such, but that disappeared when I got the new coil.

 

The TPS actually stands for Throttle position Sensor. It containes a rotory resister that when the resiustance changes, it causes a voltage to develop across the resistor. The computor uses this to determine how far the throttle is opened. I beleive it varies from something like .6 - 4.7 volts. The map sensor is actually a pressure transducer that tells the computer what the pressure is in the intake manifold. The ecm uses this to ajust the fuel delevery tot he engine.

 

This will probably sound like a huge request, but is it possible for someone to write a guide for WinALDL? I barely know a thing about any of this computer stuff and what I've read online has confused me more. Included could be:

1. tables of acceptable values
2. better, more simplistic explanations of what does what
3. ways of tuning these sensors

I can't think of anything else right now, but I probably will. If someone can do it, your officially a *** :hail:

-=-Mike

 

Drop jonas a message... he wrote it(ur talking about the freeware thing im assuming), so im sure he'll help... His SN on htis board is JoBy. Another thing that helps is learning all of the abreviations for the sensors and componemts. Personally, i think his excell type format is great, then again, as an engineer i practically live in excel

 

I can't believe they censored g0d.

I've talked to Jonas a few times and he's always been willing to help, its just that when I'm there in the car I get confused. (I didn't pass engineering Calc II, thats why I'm going to law school).

I suppose what I would really like is just something that when I'm at the track I can take out and flip through for some reference.

-=-Mike

 

aight... first thing is to get the most up to date version... it even supports the crappy ecm that they use in my 88 rs. The first tab gives you raw data, stay out of this one because it has to be converted over to useful quantities that you can understand. The second tab marked flag data contains a list of current operating paramiters such as closed loop mode or diagnostics mode. When the ecm detects one of these, it will place a check next to it. Sensor data is one of primary interest, It converts all the sensor data from raw output to values you can understand. It then places the converted values in the converted column andthe units of that data is in the next cell over to the right. In the error codes section, it just places a check next to any stored/flagged error codes. Im not too sure about BLM (block learn multiplier, i think), or INT. Theyre presented on a table that has rpm and man. abs pressure as its axis but i dont know what its supposed to represent... I beleive with the o2, it highlights the box where the ecm flagged a rich or lean cond. and places a value there, i think. Spark counts just represents where the ecm detected knock. Again it will plave a value in that cell. Again it gives you RPM and MAP (% atmospheric pres.) so you know at what throttle and RPM it occured at.

This is all useful for when you are tuning the engine. It can help adjusting the mixture, timing, spot error codes. Also good if you burn your own chip. I havnt had to do any of this yet... Not untill next month when i finnally get a new motor to replace my tired, old, slow but still functional 305

The readme is also a good place to start, It doesnt say everything but it helps alot.

abreviations to help also
IAC=idle air control
MAP=Manifold Abs. Pressure
TPS=Throttle position sensor (also given in percentage open throttle)
O2= oxegen sens. voltage varies between ~200 mV and ~1 V

 

lol... if you bug him enough he'll probably make a simpler readme with illustrations and step by step instructions made for the rest of us...

 

IMHO, i think this kind of program is most useful after you make a run at the track or do some driving, record the values it recieves from the ecm and later you can generate tables and plots of the data so you can see what is happening at each rpm and throttle range.

 

whats the best timing for my stock LO3? It seems to lug sometimes under heavy throttle and it is set now at 0 BTDC. only mod done to it now is no pipe 6inches after the cat.

 

what year is it? The 88's need to be timed to 6 deg BTDC. I have mine at eight. If its one of the later years than it should be timed to 0 deg BTDC. You could probably get away with one or two degrees of advance. Just look at the lable on the underside of the hood... that has the info there.

 

well its a 90 model RS. i would look at the table but unfourtunatly i got a $600 paint job (and believe me you get )what you pay for) and the guy painted overthe underhood stuff. im going to the chevy place tommorow to get some brakes so i want to get them to readjust my timing.

 

a 90 is set from the factory with no advance, you can run a couple of degrees advance though and you should notice some better performance.

-=-Mike

 

guess ill leave that alone then. I know this is off topic, but any reason why im getting that slight knock under 3/4-full throttle? It sounds like im lugging it but i figure 25 in 2nd isnt lugging. Sounds like the valves but ot sure. car runs fine otherwise. also if it was the knock sensor i should get a code, but nothing. Thanks in advance

 

Does it happen all the time or just when is cold and still in open loop?

Steve

 

hapens in closed loop too. i noticed also when i get on it and slowly let out it kinda surges forward for a sec but dunno if thats related.

 

The number I posted for wires is wrong and I'll fix it the second I find the correct one.

 

I ran 5-6 deg. advance with the stock cam and 8 deg. with the LT1 with no problems (93 octane)

Everyone seems to hate the Bosch Quad 4 Plugs but I've been running them for a while with no complaints. I noticed a smoother idle and couldn't tell of any lack in performance.

BTW, why do you guys dislike them other than the lighter wallet?

 

The four electrodes keep the fuel mixture from getting to the spark as easily as a single electrode. You might say it shouds the spark.

Steve

 

is that a good or bad thing??

 

That's a bad thing. This might not be well understood but the direction of your spark plugs aim is a hot rodding trick. You want to aim the open end of a spark plug to the intake port. There are a couple ways of doing this but the easiest is to just use washers. If you want proof, just read up on any hot rodding book or for hard evidence look at your spark plugs and notice how one side seems to look leaner than the other, uneven.
You want the spark to have contact with as much air/fuel and when you have multiple pieces of metal in the way it does a few things. Now this might get confusing but I believe that the 4 prongs are there for fool proof reasons like 3 not working except for the one that is furthest away from the intake port. If this was the case then the plug electrode wear would be less and hence the longer life of the plugs. I'm by far not an expert but I can think of a lot of reasons why you would and wouldn't want to use those plugs. It comes down to preference but I'll tell you now that the fast guys aren't using special plugs...they're aiming thier plugs!