Terrible running SC'ed SC400

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ihiryu

Member
Messages
245
Location
TX
Okay guys, I haven't driven my SC for quite some time since I was working on another project.

So here are the specs:

92 SC400,
Fish Bracket
Vortech V1
Stock ECU, injectors
removed EGR
W58

Pretty much after the blower the car has ran like straight crap. The car bucks and misses when I'm driving, unless it's WOT. I can watch my wideband just dance around. It'll go rich, lean, rich, lean, and sometimes it'll just run good.

I've swapped ECU's, and checked codes, the only code I get is for the EGR delete stuff.

I've replaced: plugs, wires, O2 sensors, KMV sensors.

Originally I had it ran Blow Through, and it began to ruin the sensor, so I extended the wires, and put it on the intake side of things. It virtually made no difference. I thought the bucking was from the KMV sensor going bad, thus I moved it.

I put a new KMV sensor, and the car still runs virtually the same.

If I unplug the KMV sensor the car runs pretty good, except the gas mileage, the wideband sits are 12:1 at all times.

I have no idea what's going on here, and it's driving me mad.

The only thing I can think of is possible the left bank cam sensor, since the fish bracket kinda pushes on it, but it's a pain to get to it.
 
Oh, I noticed the car runs a bit better when I first start it up in the morning (doesn't buck or hesitates as much), but I replaced the CTS and that made no difference.
 
Replaced the two cams sensors, no change.

Checked for a vacuum leak, no leaks. Swapped in a new coil and moved to both sides, no change. Going to replace the crank sensor in a minute. And trying to find another TPS at the moment.

After that, I'm going to add a rag plus a lighter to finish up the combo.
 
Changed all timing sensors and no dice. So I did make some progress, I was running without an air filter because it sat in the front bumper with nowhere else to go, I moved the KMV sensor as best as I could where it sat outside of the engine for temporary testing.

I noticed that my air filter adapter had a hole on the tube. So I placed my hand over the opening of the MAF adapter, and the car began to run better. I added a filter, and plugged the hole on the bottom and bam!

Super good idle. She idles at 13:1, and drives much better, but still not good. It's still bucking and studder, but so much better.

So the KMV sensor sits in the original location (under the driver's side headlight), and the filter portion sits behind the intercooler. I wonder if need to move the KMV sensor further away from the blower. The only problem is that space is VERY limited. I have no idea what else I can do though.
 
Could it be that your system simply needs more fuel than the stock ECU delivers? When you unplug the AFM the ECU drops onto a default map with more fuel -car goes better. Putting your hand over AFM restricts air flow increasing mixture - car goes better. Have you checked your fuel flow? pressure? . Another test would be to flick a variable resistor onto the ECT circuit in place of the sensor and dial the temp down and see what the effect is. I do it with a scan tool attached to monitor what the ECU sees but as long as you use the specs you should be pretty close. I always use an aftermarket ECU when supercharging and it solves lots of issues.
 
I don't think so to be honest, since when I'm driving it's not at boost. Just cruising. I'm going to find some way to move the KMV sensor I think that's my biggest problem.

I have an Adaptronic E420c (I think) I just need to figure it out how to wire it up though.
 
You forgot to mention you're running a blow off valve. I forget which thread it was in but I don't think it's necessary that to run a blow off valve with the centrifugal setup. Another person on Lextreme had issues. I'm not to knowledgeable when it comes to superchargers but I think everyone just recommend he run a bypass valve.

Hope this makes any sense. I'm just trying to help. Hopefully some people who HAVE run vortech can come in here and help you out. I think this would get more exposure in the Forced induction thread.

I just really want to see this setup work as I plan to go this route in the future.
 


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