Ok . So I am a complete newbie to tuning and have spent the last week doing a lot of research as to how I want to tune my car. I have an 88 Trans Am 350TPI. Motor has been rebuilt and bored to 355. Aluminum Heads Edelbrock 60859 with 1.52 rollers. Comp Cams Camshaft 08-501-8. Edelbrock TPI High Flow intake with Edelbrock Headers. 3:42 rearend. 24lb BoschIII injectors (Thanks to SouthBay). And there is no Cold Start Injector on this motor. My guess is it is a late year 88. Original Prom is AKXZ using the 32b definition.

After doing much research, everyone seems to be going to $6e code instead. So I thought I would as well. I have an autoprom from Moates. Great guy to do business with. Highly recommend him. Also I am using TunerPro RT v5. I have a couple of aftermarket chips as well (Fast and Jetchip). Funny their codes are the exact same. They are $32b code.

So I took some time and did 3 test runs with some 91 oct gas and boosted it to 98 oct. Each test I ran different chips in my car to test how they worked and with what. No mods to the bin yet (because I am still learning) except for turning off the vats. I took an ARAP.bin (vette bin), APYU.bin (89 Trans Am, this is suppose to be the same specs as my 88, just with no cold start), and Jetchip Stage 2(88 Trans Am).

In each one of these runs I have noticed that at WOT I am getting a Knock Retard. But, it is not the same amount of Retard everytime. But between all three, including the APYU chip, which is to be the stock one, I am getting a significant amount of Knock Retard. Which is about the same as the others. Also side note. This also is happening in my AKXZ.bin with the $32b code.

Now to my question. What could cause this? They all seem to make my car run very well. Although the ARAP.bin makes it run the best. But with this being caused in all 3, I am not sure which one to start with to edit. Or with me being a newbie, what to edit IE. Spark table or another table.

I have attached my datalogs from Tunerpro RT for people to look at so they can get a better idea as to what I am asking. I apologize if these questions have been asked before, because I know they have on a single chip basis. But this is with 3 different chips and all happening in the exact same area. WOT

Could the Knock sensor be bad already? Or am I not doing a thorough enough search to find the answers? If so, I am sorry.

Thanks.

 

If everything mechanically is sound then add PE first if that dont work pull some timing out. Looks like your maxing the maf at about 3100rpm so chances are you need to add in PE.

 

Thank you for your reply.

I did some more research using the datalogs I posted. I notice there are a lot of Knock Counts. Now some of them may be true with the knock retard (when going WOT only. Also on starting the car) But the rest of the knock counts I think are false knocks.

I have checked for detonation via looking at the spark plugs. No signs of wear on them from that. Although for a couple years before I got my Air/Fuel Monitor I was running pretty rich (plugs did show that) . Now looking at my data it looks like I am running pretty close to where I need to be 14.3 to 15.6.

I have adjusted for what you stated; adjusting the PE vs RPM adding some in there. No change. And then I took some spark out in that range that was affected from 2200 to 3600 in the load of 208. Still had the same knock retard with no change in the amount. Figured there would at least be a little change in it. But none

So I am thinking that this may not be a prom tuning issue. I do have pretty tight bushings (Polly Urethane) and motor mounts. Also, I notice that it will only knock retard when I have to kickdown the tranny. Basically it drops to 2nd gear from 4th When going from 4th to 3rd it does not knock retard. Also just a bit on startup it will knock retard, but only during crank to fireup. Crazy to me.

Has others noticed this with their datalogging? Or any other ideas to try?

Appreciate the help.

Thank you.

 

Forgot,

Thought I would also put in that when this knock retard is going on, I do not feel and difference in power. Not saying there might not be some. But it is not noticeable by bogging down or slowing down on acceleration.

Thanks.

 

Well if its only happening when the trans kicks down then its most likely noise, if thats the case the you can adjust the knock sensitivity.

 

That makes sense. But I think to be safe I am going to change out the Knock Sensor as a safetly. Since they are only about $30.

Here comes my Newbie issue. How do I change the sensitivity on it?

Thank you for your help.

 

Just looked at a 6E XDF and it looks like the only thing you can do is reduce the maximum spark retard in pe (this is pe only and I believe its only happening while your in pe, you could also reduce when not in pe) in the rpm cells, just make sure its not real knock but you could just leave it if you dont here any pinging and you really dont feel to much power lose.

 

It is normal to get knock counts during cranking. A lot of noise is created when the starter engages the flywheel.

The downshift knock also occurs but is a nuisance. As it will reduce the SA and cause a loss of performance.

If/when you replace the knock sensor, the torque spec is 11 to 14 ft/lbs. Not much more then hand tight. And it is in the water jacket of the block, so have a drain pan handy.

You can make the sensor less sensitive by using a 45* street elbow between it and the block (plumbing part).

If the tune is OK, can also increase the decay rate so that the retard goes away faster.

It is also helpful to learn about spark plugs and how they should look. Small black specs like fine pepper is a sign of detonation.

RBob.

 

gp90gta :

Thanks for the information. I will try reducing the PE and let you know what I find out.

RBob :

What you stated about the 45* elbow and hand tight is exactly what I am going to do. I got everything picked up today for that and will work on that tomorrow.

What you stated about cranking and shifting makes sense in creating a knock. I have ran my car hard a few more passes and rechecked my plugs again. Nothing on the APYU or the Jet Chips. But I had a little tiny bit of detonation show up on the ARAP one. So I believe that one has too much advance to it.

I will keep you all posted. Thank you,

 

Woo hoo. Changing the knock sensor and adding the 45* elbow helped a lot. No more false knocks. I do get an occasional knock when going from 4th to 2nd gear still. But instead of several knocks it is only one.

Now on the the BLM's and idle.

Still researching on those two and what tables to change those in.

Thanks for your help.

 

Go by the BLM values, the INT changes too quickly. You want to change the MAF tables to get the fueling in line. Note that the ones in ARAP appear to be the most accurate. Don't forget to hit the Tuning Guide Book sticky up top the more information on tuning MAF set ups.

RBob.