My car was running pretty ****ty for awhile. I like to tinker with it when I have time, but the last few months my time has been pressed. Basically, the more miles I'd put on the car, the slower it would feel. So i'd reset the PCM, and car would run decent, then 200-500 miles later it would start all over again. Got to the point where I was convinced the car would drop 2 or 3 cylinders going WOT. Funny thing is the wideband is always spot on 12.5 AFR, so it had me a little confused. Finally got a new battery for the laptop and did a datalog to see what's going on.

Well, everything looked great except for the fact that timing advance was only 25-28 degrees. I figured the LT and RR were a little noisy for the LT1 KM. Found a LT4 KM on ebay and installed, super easy BTW. Put 1k on it so far and the car runs great. And I know you can modify the PCM pulling timing in Tunercats, but when I get the blower hooked back up I definatly want it pulling timing when neccessary. Also, fuel mileage is now around 20 (HW/city mix), vs 16 with the old knock module.

 

Nice! Not a bad fuel economy increase by any means. I know about 15 truck drivers who might even kill for an increase like that. So exactly how was it running bad? Just rough at all times, or were you getting engine shake, etc? Just curious.

 

sounds like some Knock retard. I put a LT4 KM in my car and it didn't really help me much. I still get 6* or so, but much better than 11* that I got on my dyno pull with the stock module!!! sent the ECM to madtuner to see if it goes away.

 

Didn't run rough, just lacked power. Throttle response from cruise to WOT was AWEFUL, seriously felt like a 4 banger. Car wouldn't pull hard to redline either. And I got 4.10 gears, so it should be snappy.

 

keep us posted.

 

Gotcha. Yeah, keep us updated on how that works. I didn't even know the Lt4 could be put on an Lt1.

 

Ya the knock module is plug and play, plugs into the pcm. LT4 KM is a little less noise sensitive because the LT4 RR from the factory, which are a little noiser.

The one test I haven't done yet is hammer on the car to see what MPG it gets. Before it would do are 12-13mpg when I would beat on it. I've been cruising the last 1k to check for consistency.

 

Okay, nice. Yeah that would be interesting to note. Once you lay it on the car a little, update us on the MPG.

 

I see you have a 94, my question to you is: do you know if the OBD l and ll KM's are the same. My car runs like its stock again and been trying to figure it out also. But it does not run as bad as you described.

 

Not sure about the odbII, http://shbox.com/1/lt4km.jpg shows 94-95.

Just gave her hell here and there, 18.3mpg on the last tank, still running good.

 

The knock modules are the same OBD1 V OBD2...the knock sensors are different.

 

tnks, cuz im to lazy to typr thank you......

 

Might have to pick me up one of those. Dang, 18mpg running hard, eh? That's what I like to see.

 

You will not see any difference in performance or in MPG with the LT4 KM, unless you happen to be getting excessive "false" knock retard. That can be checked with scanner. Putting the LT4 KM in the PCM of an engine that is not experiencing false knock retard is not going to change anything.

 

+1, when i bought this car it was just about bone stock. advertised mpg was like 18city/29hwy and around 23mpg if you split it halfway. When I started modifying the car, all that goes out the window.

The main reason for this thread is to help those with roller rockers and long tube headers. If you experience a similar performance loss, double check what the timing advance the PCM is allowing. Instead of getting crazy and buying new opti, plugs, wires, fuel pump, etc. right off the bat. Mine is still holding 40deg.