Hey guys. been playing alot with the tune lately, trying to get work done before the end of the good weather. i'm running a slightly modified ARAP on a stock l98, mods in the sig but nothing major done to it.

all summer i've had a slow overheating problem, the car is fine around town, but on the highway the temp steadily rises, and i mean slowly, if i do nothing to correct the situation it will hit 240* F in about 35 minutes of 65mph+ driving.

now, if i slow it down to 65 or less, and crank up the heat i can drop the temp back down at about the same rate.

so the last few day i've datalogged it and i notice right at 2400 rpm's im seeing alot of knock, my last datalog i had about 15 at 2400 rpm and 64 ish load. i've pulled timing in that whole light load mid rpm range three times but i'm still not seeing significant relief from the overheating or from the knock, are they related?

how do i post up the logs? thanks alot!

 

You have to be careful with ARAP. The timing is aggressive and not meant for the engine you are running. It isn't surprising that it is knocking.

-OR-

Maybe the knock is false knock, and you have already pulled the timing back. Too little timing dumps a lot of heat into the heads and exhaust.

To be honest, it is hard to say from this distance.

I would probably replace the timing tables with the stock SA from a calibration for your vehicle. Then see what happens. If the knock counts continue, check the plugs for signs of detonation. May need to put fresh plugs in before hand, just to get a good read.

RBob.

 

i have an l98, how much did they change from 87 to 89? i have NEW l98 at that less then 10k miles on it, thought it was a drop in replacement for the ABWT i was running before.

i've had this overheating problem for the whole time i've owned the car, ARAP for half that time, but till now i didn't know it was knocking.

 

ARAP is for a lighter vehicle that also runs the aluminum '113 GM heads.

Give the plugs a look for signs of detonation. Then go from there.

RBob.

 

rockit, have you changed the Fan Operation Switch in your ARAP bin (Normal Open Fan Request in the Switch Tables)? It needs to be "turned on" as it is normally "turned off" in the ARAP code. This switch is reversed from normal F-body operation.

If you have done the switch in the bin, have you changed the T-stat? If not, remove the thermostat and see if the temp drops. If the temp does not drop, then try running your original code...to see if the problem is in the ARAP code or not even code related (if the problem persists with your original bin).

Lastly, have you checked out your front chin spoiler? That is really important in directing air flow to the radiator on an F-body for highway driving.

But here are some of the common F-body cooling problems as well as a way to verify if the problem is in the ARAP code itself.

 

Thanks alot reaper and Rbob

1)i thought the f bodies had ARAP in 89 on up untill the SD came in, i remember reading specifically that it came in the magazine cars althouht the two are unrelated.

2)as far as chin spoiler, if you're refering to the four foot long peice of plastic that crosses the front end, then i do not have that. but i DO have the plastic ducting that seperates the air from going further forward into the nose and i also have the two and a half foot wide stiff peice of plastic that complements it.

3)i have changed the thermostat to a 160* but it didn't help bit, its a "hi-flow" peice of crap though and i intend on replacing it with my 170* delco soon.

4)the fan switch operation flag is confusing to me, i have removed my a/c so i'm not really sure which way i SHOULD have it, i know that it turns on at what seems to be the temps i set but at idle the car stays cool so i don't get the chance to often check the cycles.

5)as far as being code related, i know i;m knocking and that the car acted the same on ABWT so yes and no. knock can cause overheating right? can overheating cause knock? i would assume so.

 

1) I understood the ARAP was a bin used for some automobile testing in Vettes. But, it's all ancient history now and the real story doesn't answer your problem.

2) Make sure that you have all the front spoilers that came on your particular car - they are important for directing air-flow...and one particular problem that can arise if they are removed is overheating on the highway. So check that one out - I think that may be the source of your problems.

3) consider drilling some by-pass holes in the body of the T-stat - for extra cooling.

4) As for the "Fan Switch", there is a group of "bit switches" that are used in the various bins. On the ARAP, one of the "bit switches" that needs to be corrected is the "Normal Open Fan Request". It is normal closed (or set to "1") on F-body cars. But, on the ARAP, it is not set (ie=0) and must be set (ie=1 in the particular bit mask).

Unfortunately, I use Tunercat, which is an "easy to understand" check box. So I cannot give you the specific location address to let you know the "bit mask" that needs to be set. This is one of the reasons I prefer to use and recommend TunerCat to people - it's all predefined and easier to use for people starting out that are not aquainted with Assembler. Basically TunerCat is more "user friendly" IMO. But, it isn't free either - but you get what you pay for.

5) Yes, overheating can be a source of knocking...and vice versa. But I think in your case, that the overheating is due to some other reason - unrelated to the knocking.

 

okay, welp if that second spoiler is that important i'll have to source one and see.

thanks alot for the input Reaper and Rbob, hopefully by spring we'll be in business.

 

As for the "Fan Switch", if you post your bin, I will take a look and see if the Fan Switch is set properly for you. If it isn't, I will fix it for you - but you will owe me a beer (standard fee for small quick changes).

 

okay, whats the address for "the bone yard"? what kind of beer does the angel of death prefer?? probably some molson triple x?

could we make it a six pack? i've been fighting with my "crank" tables, seems i've missed something in there cause the car fires for a split second almost as soon as the key is turned then tries to fall on it's face the next second, 70 percent of the time it makes it and starts despite this, the other 30 percent of the time i have to try again.

thanks alot reaper.

 

Hmm, I replied yesterday but somehow TGO lost my post.

Anyway, you have that switch properly set so there is no issue with that. I have a feeling it was that "chin spoiler" that is causing your overheating issue on the highway. This is a common problem (as it often gets knocked off/damaged over the years from hitting sidewalks/parking stall curbs).

I haven't looked at the rest of the bin as I am quite busy and currently suffering health issues - so time is very limited (usually just answering a few posts on TGO). But if you have anything you specifically want me to look at, let me know. But please don't say "everything".

 

well,,,really just the cranking stuff, the startup tables. there's no rush on it man. i know its software related as it used to start AMAZINGLY well on ABWT and now it chokes for a second, starts faster but less reliably ever since i did the mod to the startup tables. i changed the one table that cuts out the fuel for a certain number of reference pulses so that it doesn't anymore, and played with the temperature related startup table but obviously it's hard to get that table dialed in as you can't just keep starting and stopping the engine without changing a few variables..

hope you feel better man, thanks for the help!

 

whatsup guys, just asking if you found anything grim. How are you feeling? did my beer get to canada? i tried just writing the address on the side of a bottle and stamping it but the guy at the post office didn't seem to like that.

 

Don't know if this will help or not, but I had a similar starting problem when i switched to the ARAP code. I made a few changes to fix it, but the one that helped the most was looking at the "Startup Spark Advance Vs. Coolant Table". In the ARAP code it's all set to 0's. I copied over the figures from the stock bin and that helped quite a bit. I also found that just moving the value down a few levels in the "Crank Fuel PW Multiplier vs. Ref. Pulse" actually gave a bit too much fuel, ended up going with .35 instead of .50.

 

thanks i'll check that out and maybe burn one before work tonight.

 

so, i have 5 degrees advance in my startup timing table, the one that is referenced by temperature, does that mean it adds 5 degrees to the base timing, or is it 5 total? and how do i setup that table for the temperature differences?

 

I would like to know also

 

Typically a startup table (both fuel & SA) is for a short period of time once the engine is running. The purpose is to help prevent stalling once the engine catches (from crank) and starts running. Basically this will add SA and fuel which is quickly decayed out.

The amount of fuel/SA and how quickly the decay is is both based on CTS (typically).

RBob.

 

hey grim good to see you around the boards, how are you feeling? did you ever take a look at my startup tables??