I've been getting zero help from the C4 section. My 93 failed emissions back in July and I've been trying to resolve on my own, with zero help from the forum and misleading help from local mechanics.

I have a 93 with the LT1, LT4 hotcammed, longtubes, high flow cats, B&B exhaust, MSD. Slightly larger injectors and a mail order tune from PCMforless.

So far, I've added the following

remanufactured ECM
new accel 24# injectors
New heated AC delco O2's
New AC delco plugs

Last year it was the cam, new distributor, wires, coil, fuel pump, IAC, Knock sensors, the list goes on.

I'verecently purchased the scanning software, Datamaster to see what is going on but I'd think I've expended enough money and time resulting in the same problem. Anyone you'd reccommendwould be greatly appreciated.

 

PM Mr. Mojo he might be able to help you.

 

not that you want to hear it, bit brian from pcmsforless told me NEVER use accel injectors and that half of his headaches are from them. I used a set in a 94 Z28 thats heads/cam and still has trans problems, buddy just isn't in a rush to get it operational.....

he said go with the ford SVO injectors.

 

Believe me, I've researched when purchasing the new injectors. Iwas aware ofthe Accell problem but was told their newer silver top injector was very good. That's what I have in there.

 

Have you tried posting in the Scan and Tune section? Pretty knowledgeable people there as well as C4 Tech.

DId you **** anyone off? Maybe that's why you aren't getting any help?

 

I don't think I've pissed anyone off. I'll posttopics related from day 1,when it failed. I've bounced from the tuner, to one mechanic to another. In the meantime, I've been asking help from the C4 section. Did it sound like I pissed anyone off?

http://forums.corvetteforum.com/show....php?t=1804821
http://forums.corvetteforum.com/show....php?t=1800676
http://forums.corvetteforum.com/show....php?t=1805023
http://forums.corvetteforum.com/show....php?t=1805128
http://forums.corvetteforum.com/show....php?t=1806003
http://forums.corvetteforum.com/show....php?t=1807599
http://forums.corvetteforum.com/show....php?t=1818086
http://forums.corvetteforum.com/show....php?t=1827913
http://forums.corvetteforum.com/show....php?t=1838456
http://forums.corvetteforum.com/show....php?t=1840796
http://forums.corvetteforum.com/show....php?t=1842123
http://forums.corvetteforum.com/show....php?t=1849242
http://forums.corvetteforum.com/show....php?t=1850718

Since these posts, I've called Alvin from PCM and ordered a new chip. He's awareofthe problem and hopefully he can help but it would be nice to have someone somewhat local to go to.

I don't expect anyone to go through all the above posts but it seems as if I'm walking down a never ending road. Seems like C4 tech is mechanical and C4 scan and tune, you need to know about scanning/tuning to get advice.

All I'd like to do is find someone, or a garage, who can understand what is going on. I've probably spent around $1000 so far and I'm still where I was back in July.

 

Some detail on why it failed and the stats from the test would be helpful.

Most times, the idle tune is waaay off from cammed cars. Larger injectors, cam, free-er exhaust all spell "trouble" on a sniff test. Is that what RI is using?

Found why it failed. Yea, it's waaaay toooo rich at idle. A competent tuner needs to burn you a new chip. Not mail order! They need to work with you at the car, on the car.

If you find someone with your exact modifications-- you may get lucky to have a duplicate file burned.. but it's a waaaay long shot. Regardless of the mods, sensors and component tolerances make every car unique

 

I'm asusming a "sniffer test" relates to what the guy used to measure CO and HC, the probe in the tailpipe?

The mail order is the only way I can go unless I can find someone or trailer the car to CT, NY,etc.

I've called one shop 20 miles away about 3 times, left messages with the secretary and I got the feeling nobody wanted to work on an LT1 car. The 2nd shop,which I originally had a tune and brought the car to him after it failed, told me it wasn't the tune and is closing up shop. I can never get ahold of him anymore. I've called corvettes of westchester last week but never got a response. These circumstances led me to do a mail order tune trhough PCMforless and hopefully Alvin will work with me but like you said, the tuner needs to be at the car.

 

You need to find a shop that works on high performance cars or a friendly service station. There is no reason why a pre-1996 car can't "pass" inspection under any circumstances.

 

I hear you, Finding one has been difficult.

Someone posted to try and search for exhaust leaks or vacuum leaks. I came across this. I'm going to correct and see if this helps any problems.

http://forums.corvetteforum.com/show...post1562552181

 

Good luck, wish I could help more.

 

Look I'm no mechanic so I'd like to pass this along from the ZR-1 section. Quite a few of the guys with LPE and DRM cars have cam changes that cause issues with exhaust gas analyzers. Most of those guys use methanol as an additive to the gas right before the test is done. Also, they get the car waaaay into closed loop operation temps.

You might try searching the ZR-1 section here @ CF as I know that there have been threads on this issue. LT5's are notorious carbon machines and I know I've seen this issue discussed in the ZR-1 section.


Tom

try searching in the ZR-1 section using the screen name RKreigh as well as the "Failed emissions test".

 

Tom,

I'll give it a try but I don't know if the problem will be solved using methanol, especially if it failed almost twice the legal limit.

 

This is really stupid....but I'll throw it out anyway.:o

Do you still have your OEM EPROM? If yes, I would throw it back in and try an exhaust gas scan again...if anything it shoul be leaner than the fuel mapping on the super chip you have.

My reasoning goes like this: from reading all the threads you listed I found some things I don't understand.

Spark plugs looked bad rich = bad ignition &/or bad fuel trim or restricted air intake.

O2 sensors (single wire variety) looked unbalanced = that's nuts because they should look almost the same, which leads back to #1. Or one bank was way lean w/bad injectors so the other banks' injectors were the only ones to respond to ECM's fuel changes....which still goes back to #1..kind of.

You are now using 3 wire (heated) O2 sensors? I didn't know that was possible on a fuel map designed for unheated O2's....but this is where I'm not fluent in EPA speak.....ZR-1's used heated O2's because of the cam & intake set up and the fact that till the LT5 there were no speed density fuel metering systems used on corvettes....I think that was the case even with the LT1 & 4 motors....wasn't your motor a MAF system? An LT5 just has a MAP sensor.

I'm gonna go look up the ZR-1 threads on emissions' failures....I'll be back....this is pi$$ing me off.

Tom

 

OkayI did some checking....not done yet!! but here is some stuff I found at our forum...not here......http://www.zr1netregistry.com/forum/...iled+emissions

http://www.zr1netregistry.com/forum/...iled+emissions

http://www.zr1netregistry.com/forum/...iled+emissions

I'm gonna look here at the ZR-1 section later.


Tom

 

Hey Justin,

Try calling J&M corvettes or J&M Motorsports in Manchester, CT...whatever they call themselves these days. They do state emissions there(albeit CT emissions), tuning, as well as having a dyno....maybe they can help you out.

 

Just a shot, contact Don (slowhawk) who works out of DEZ in Seekonk. Don works on the LSx motors, but maybe he has some other contacts that could help. I also think Mike at DEZ burns proms for Mustangs. Not sure if he can help you at all but it also doesn't sound like you are getting very far now either.

One other thought, is there a software version ECM that can replace what you have, at least that way it could be programmed real time.

 

I haven't been getting very far besides testing sensors and datalogging. Funny, O2, TPS and MAP on TTS datamaster read way off compared to actually testing voltage at each particualr sensor....

Either way, I might be getting in too deep and will call both shops on monday, thanks for the info.

 

DEZ is a no-go with LT1's

J&M (mike) is going to call me tomorrow. Guys sound cool and looks like they can help me out.

 

Hope it works out