MDZ28

This is all new to me and I recently switched my motor with an upgraded cam. see signature. When I received the cam it stated that it need to be tuned after installation.

my car was fine for the first week or so of driving, but still didn't have the torque I remember and the Horse power I remember feeling in the old motor that I took out (which had 180,000miles on it.)

After that first week my car felt like it was in limp mode and would hesitate and sputter in every gear and while cruising at 60mph it would serge.

My check engine light was on and I have a dtc 26. It is the evap canister. Which my mechanic said he didn't think a evap canister would cause the issues I was having (unless the car goes into limp mode when the check engine light is on)...

Anyways Long story short, I was wondering if anyone with the lt4 hotcam and 1.6 rollers needed a tune before the car ran properly?

If so where and how much is it to get at home programming software? Ive looked on Tunercat.com and saw the ($EE Definition program byte) option but how is that used to program/tune a pcm?

Injuneer

Tuner cats, EFILive V4 or LT1_Edit. Not an easy DIY. Best thing to do is a mail order tune from someone like pcmforless. They have done so many tunes for basic mods like you show that it is likely you will get a good tune.

Yes, even the LT4 HOT cam needs a tune for the best results. They can net you 10-15 HP on a totally stock setup. You'll likely see a lot more than that with your mods.

DTC 26 is for the EVAP purge solenoid on the bracket on the passenger side of the intake manifold. Code is totally set by a faulty electrical circuit, really has nothing to do with the canister itself. The code does not cause "limp mode". Virtually nothing to do with codes puts it in limp mode. That comes into play when the PCM loses almost all the inputs it needs to run the engine. Most codes cause the PCM to run a default/backup routine that will probably not even be noticeable.

MDZ28

I was looking at pcmforless, do you know the basic prices for the tune? There are no prices on there website.

MDZ28

just got off the phone with pcmforless, its $190 for a tune. I answered my own question

Thanks for help, I'm going to get a new pcm and a new flash and see if that fixes all my issues. I will update this thread if it does.

MDZ28

So I put the new pcm In and the check engine lights are off as I had them tune out VATS, EGR, AIR, AC, evap and cat converter.

My problem of hesitation is still very much there though and my car still feels like a sub 250hp car and doesn't not run very well.

Very discouraging...... I keep throwing more and more money and Now I haven't a clue of what to check for next.

I was thinking maybe the gas has water/condensation built up in it?

Maybe my fuel pump went bad? Even though It has less than 5,000 miles on it.

Any suggestions? Ideas?

I'm about to give up

Injuneer

Fuel problem would show up with a pressure test, engine under max load - WOT over 4,000 RPM. Tape the gauge to the windshield.

If fuel pressure holds, time to run a data log with Scan9495.

Do you have a cat? Plugged?

Personally, I wouldn't have deleted EVAP.... keeps the fuel smell from stinking up the back of the car.

MDZ28

The fuel pressure is ok; we tested that earlier today. At WOT the car runs like a champ, under load in the lower rpm's is when it sputters and hesitates and there's no power. It seems like there is no torque.

As far as the Cat, it is a stock cat that was previously gutted.

I'm assuming Scan9495 is a computer program? If so where do I download it and is it expensive? Along with scan9495 is there cables I need to hook up to the car and any extra information you have on the subject would be great.

You have been a great help to me and I couldn't do this without the support.

A side note:

As far as the evap goes, I was told by the tuner that the system would still work but it wouldn't trip the codes.

Injuneer

Scan9495 is the best LT1 data logging software - PCM, ABS, SRS, ABS. Written by an individual who is a member here. Free download, you supply the cable. Go to the "Computer Diagnostics....." forum (this forum) and look at the "sticky" thread at the top of the forum topic listing. I (and a few others) can interpret the data log for you.

The LT4 HOT cam moves the torque curve upward, peaking at higher RPM. May not feel torquey at lower RPM. Was the cam degreed when it was installed? The full roller rockers make noise. The LT4 has a special knock module to filter the noise and prevent false knock retard. Do you have an LT4 knock module? The scan will tell you if you are getting knock retard under low RPM load.

If you don't purge the EVAP canister, eventually it's going saturate, and stop adsorbing the hydrocarbon vapor. My (track only) car has the system deleted, and you can get a real buzz from the fumes of 116 octane VP Fuels C16.

MDZ28

Thanks for the info, as far as scanning goes, I do have a snap-on Scanner with a 12 pin connector that scans my car. I have scanned the car at idle and there is no knock retard even with 3000+revs (I'm using a stock lt1 knock sensor). It is funny though because I got a code for the first knock sensor I had and replaced it with another lt1 knock sensor I had in my shop and the code went away.

I will drive the car this evening and scan it while I'm driving to see if anything is off. I will have to download the scan9495 software later this week as I don't have a laptop to use in the car as of now.

I also didn't do the build or cam work so I'm not sure if it was degreed. I'm assuming it is in stock format.

I also do smell gas but it is not terrible. I'm running 93 octane.

MDZ28

Drove the car today with the mechanic. The sputtering I though I was having was diagnosed as a misfire...

He said It felt like the car was running on 6 cylinders (which explains my car feeling like a sub 250hp car) and he said we will check the spark plug wires and where they hook up to the front of the opti.

He said were gonna have to check these first as the the other option of replacing the opti is a PITA and costly.

MDZ28

Ok so I checked the spark plug wires today and found out one of if not THE problem(s) with my misfire.

My wire on the right side Of my motor fell off into my hand when I tried to removed the boot from the plug.

I added a picture showing where the wire was dry rotted and arching to the headers. You can see where the heat was radiating through the wire. Its charred from the inside out.



I'm looking at these wires as replacements. Are these good? Or do you recommend something else?

MSD Ignition Super Conductor Plug Wire Set 32149: Advance Auto Parts

MDZ28

So I replaced the spark plug wires and they all had numerous dry rotted spots. They also had chunks taken out in various places throughout the wire (like mice had been chewing on them or something).

Anyways I started the car up and it runs like a champ now. I finally have the feeling I remember with the old motor but its a lot faster

Glad to finally have a working car again. Thanks to everyone who helped out over the numerous threads.