Hello folks, I just picked up a 88 coupe, If I sound ignorant about the L98 I apologize , I never had a L98 , (LT1,LS1 vettes yes), but I went back to the C4 for cost reasons, I picked up this very very clean 88 for a good price.

With that said, it has a Procharger P600B with a intercooler, along with the installation of these mods which were 4 years or 4500 miles ago, I am told they redid the heads to accomadate the blower and valves and port matched the heads to aftermarket intake runners (big fat runners),Roller rockers, it has a boost guage and air/fuel mixture guage in a pod.New Tranny was put in at that time also with a shift kit.Vehicle has 3:07 gears.

I was told the procharger puts out 8lbs of boost, again excuse my ignorance but what should the boost guage read while normal highway driving, in the vaccum readings, and then when you accelerate it goes into the boost (psi ) numbers correct.And the air/fuel guage is all over the place, it never stays in one place (lean,ok,rich).

On the way home today from picking up the vehicle I noticed the "service engine soon" light came on, called the previous owner up and of course was told he has never seen it go on, (and he seems like a honest older gentleman), I notice it came on when I stomped on the gas on the highway to pass.Also heard what seemed to be major spark Knock

I am guessing that the system just needs to have a proper tune.

Does anyone know what the factory timing setting is on the L98 (emission tag is not on the radiator shroud anymore), or if possible what setting it may need to be running a SC'er.

Thanx for any input


After running the codes , 43(electronic spark control) is the only one showing, any ides, so I replace the control module, or do I need to do any other tests.

Thanx


And any other useful info on this setup would be greatly appreciated, as this is my first trip into the forced induction world.


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Wow sounds like you picked up a pretty cool C4, I am no expert at FI but I would ask the original owner if the prom is factory or if he had a mail order one, or if it was tuned. If it is factory you may want to get it tuned. Have fun with it.

 

[QUOTE=
I was told the procharger puts out 8lbs of boost, again excuse my ignorance but what should the boost guage read while normal highway driving, in the vaccum readings, and then when you accelerate it goes into the boost (psi ) numbers correct.And the air/fuel guage is all over the place, it never stays in one place (lean,ok,rich).

Does anyone know what the factory timing setting is on the L98 (emission tag is not on the radiator shroud anymore), or if possible what setting it may need to be running a SC'er.

Thanx for any input

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During normal cruise you would be probably in the -14 to-10 range of vaccum, of course when you stomp it. It should show boost if it is 8 pounds as he claims you should read about 8 pounds on the guage..

The AFR will dance around as you are cruising in closed loop... when you go WOT or into boost you should see it settle down and be in the 11.5 -12 range depending how rich it is tuned...

It has been awhile since I have worked on a L98 while the above will still hold true. I want to say that when you disconnect the timing lead and look at it with a timing light I THINK it was like 10 degrees BTDC maybe 13 .. the other thing you need to check is be sure you have enough fuel pressure under boost...

If you are seeing anything higher than 12.5 (13.8 ish) while in boost I would keep your foot out of it, if the numbers start to climb to high 13's you best let up that could be an indication that your fuel pressure is not where it needs to be... Also if there is a timing retard on your igmition make sure you are at least set to 1 degree per pound of boost, get your self a logging program to check your spark knock...
I hope this helps feel free to PM or email me if you have more questions...

MO

 

Thanx for the input folks, to answer some questions, the previous owner said he had a Hypertech module for it but removed it because it ran better with the factory prom, I would suspect that the Hypertech prom he put in wasnt for a supercharged setup.

Does anyone have any input on the error code I am getting #43 which is the electronic spark module problem.

 

Reset the codes and see if you get the same code again.

With regard to timing, factory spec is 6° BTDC with the weatherpack disconnected. You should leave it set to the factory setting until you have a chance to get a professional tune.

I feel certain that the A/F ratio meter is a "narrow-band" unit that reads off either the factory O2 sensor or a duplicate "factory-type" O2 sensor. These are the units that typically read lean/OK/rich (or red/yellow/green). For this reason, it is pretty much useless. However, a cockpit mounted wide band O2 (reads a numeric value, or a sweep of actual numbers) would certainly be a valuable tool.

The Hypertech chip would mot have been for a S/C'ed application.

Aaron

 

Thank you sir

 

Thanks Aaron, it has been awhile and fully agree with you, a WB o2 is defiantely the way to go... I didn't catch the lean /ok /rich comment

Mo

 

Yes that is the guage that is in there the Narrow band, If I were to replace it with a Wide Band as suggested, can I just replace the guage head itself or do I need to reroute the wiring also.

I also checked the timing and it was way off , it was reading like 4 degrees after, reset it to read 6 degrees BTDC, seems to be idling a little better, cleared teh codes also , so I will see what happens.

Thanx again folks for the help I havent had to play with timing since I had my Boss Shinoda mustang 5.0

 

I have been in PA this week, so unable to check in lately.

Timing that is way off from what it should be set (either advanced or in your case way retarded) will sometimes through an ESC code.

The wbO2 replacement will require new wiring, O2 sensor, module and guage face. Keep in mind that the wbO2 is in addition to the factory narrow band that the ECM reads, so you will need to have an additional O2 bung welded into the header collector (or exhaust pipe, if factory exhaust).

I think that you are on the right track with trying to learn about your new car.
Aaron

p.s. Have you figured out what boost level the car is running at?

 

Thanx again Aaron, appreciate the input, as far as the boost level that I have witnessed, To be honest I just got the car off of jack stands, (doing my usual detailing underneath and what not).

So I really havent been able to take it for a good romping, also I hear a slight tapping on the passenger side valve cover , so I suspect the Roller rockers may need a adjustment, and hopefully nothing else, so I am going to take it easy until I get it to a shop for a look over.

 

I'd also pull your spark plugs and see what they look like. Being able to hear audible spark knock on a boosted engine is never good. Hopefully you won't find a smashed in plug electrode. Bob

 

Well, I did think of that , and I removed one plug from the drivers side head , and it looked normal, that doesnt eliminate the other 7. That is why I am taking it to shop, I just cant bend over to do the plugs anymore after 4 back surgerys Homee dont bend dat way no more,lol

I did take it for a spin around the neighborhood and I had no more pinging and it ran much better then before, and actually the ticking noise on the passenger side seems less audible now (maybe thats just my mind trying to trick me into believing nothing is seriously wrong,lol).

 

Tapping sound typically a rocker (which sometimes will quite as the engine warms and things expand, as well as the hydraulic roller lifter "pumping up"), while a ticking typically is an injector (which is fairly normal for many of the factory injectors, as well as some aftermarket).

I too have had the major back surgery (several fused following major auto accident), but fortunately, I still am able to do most everything that I could before. I just have to take it easy on the Sportbikes and the game of Golf and the like.
Aaron

 

Thats great, that you still can move around like before , I also was a Golf nut, actually club pro status, along with my brothers, Golfing, freestyle skiing my whole life also, But 23 years in the HVAC biz has taken a toll on the ole bones, 4 back surgerys,1 complete knee repair, 1 rotator cuff, oh ya 1 heart attack also, and I am only 45, Not complaining though, I am still on the right side of the earth so that is good.I just have to do the treadmill everyday to stay somewhat limber

Take care