1SLwLS1

iTrader: (6)

I went back and looked at that, its the crappy lighting from my cell phone.

Well, one of the MSD wires had around 850 Ohms of resistance while the rest were in the 25-35 Ohm range. I am guessing that maybe the cylinder pressures (max @ peak torque - 4-4.5K) is knocking out the flame kernel before it can propagate through the entire air and fuel mixture?

I went WOT this morning and there was one slight hiccup, but only one versus usually several and a loss of power. I will test it again at lunch time.

1SLwLS1

iTrader: (6)

While I am at it, does anyone have the wiring schematics and transformer resistance specifications for these coils so I can test them tonight?

transam19

iTrader: (1)

Not sure about resistance, but looking at ur plugs I would look at the #3 coil and #8. They seem alittle diff than the rest.

crainholio

iTrader: (2)

6 looks wet in the first pic, also note the absence of black carbon ring at the base of that area.

7 looks dangerously lean.

Skip the 3M kit, replace your injectors or have them rebuilt.

1SLwLS1

iTrader: (6)

You think so? They're about a year old with maybe 15K on them. I found a local place that will service them for about $15/injector but this is my DD and he has a turnaround time of 1-2 days.

Well, I moved the oil cooler on Saturday. I put it horizontally mounted between the front radiator support and a piece of angle running between the D-bushing mounts for the front sway bar. I put a 10" pusher on it mounted on the bottom side of the cooler.

I flogged it everytime I drove yesterday, in the morning on the way to work, at lunch, on the way home form work, 30 minute cool down and hot-restart out to a work party and I had no hiccups. The engine performed flawlessly. Since I had changed my plugs and wires, these hiccups would only occur when the engine is hot and last night I was sure the issue was a combination of detonation resulting from high IATs and a poor ignition system. I was sure I had fixed it until this morning. I got a lot of hesitation and popping on the way to work this morning. This has me so baffled. I haven't had a chance to check the coils further, not that I would likely find anything as they're a PITA to correctly diagnose. I guess I will have to investigate those tomorrow and I am getting rid of the MSD wires altogether and will go back to some AC Delco variation.

crainholio

iTrader: (2)

Unless you're running forced induction, stock plugs and red LS6 wires are hard to beat. Presuming the LS6 wires will fit your application, if not then I'd stick with stock replacements.

Katech is selling brand new takeoff Delco Iridium plugs on eBay.

The wires are reasonable at wholesale price, check your favorite GM parts source.

crainholio

iTrader: (2)

How certain are you that your cold start problem is the fuel pump check valve?

Looking at plug #6 I'd speculate that this cylinder's injector is leaking at the pintle. If so, you want that corrected.

What injectors are you running?

1SLwLS1

iTrader: (6)

I'll stick with the TR6s for 11.5:1 versus the stock plugs. I am picking up Delco wires from the local parts store tomorrow or the next day. They have them for around the same price as the MSD wires.

I'm not certain at all about the source of the fuel pressure bleeding off but the issue has been around a lot longer than the injectors. They are Lucas 42#/hr injectors from New Era Performance.

The parts queue is stacking up quite high, haha. I need/want a Racetronix fuel pump kit with new regulator/check valve, I need a fuel pressure gauge, AFR gauge, I would like to replace all the coils with new OEM units, just for good measure, haha. I have a C5R chain sitting in the garage to replace the LS2 chain I would like to get around to, I have the OE LS1 harmonic damper waiting to be installed along with a new pickup o-ring and bolt, and some Brembo rotors sitting on the shelf that need to get swapped with some Hawk pads. The hold up used to be money, now I have the money but I have no time! It's one or the other...

joecar

Sorry, I've been gone with my Mrs for two weeks...

The spark plug from #7 looks way too clean... it kinda looks like it overheated a little, possibly from becoming lean.

joecar

The only way to clean the injectors is to remove the screen as Jimmy said above, and run cleaning solution thru them while they are held open electrically.

joecar

What was different between the two days...?

1SLwLS1

iTrader: (6)

Injector rebuild?

Ha, I wish I knew, the only difference was cooler temps for the morning run where it hesitated so maybe the fuel supply couldn't match the cooler more dense air?

Aside from yesterday morning, I flogged it again at lunch and yesterday afternoon/evening. Again, no hiccups. This morning on the way to work, no hiccups. It's interesting how intermittent this is as well as how hard it is to nail down the variables. I will either order new injectors or have these re-done. I may order the same new ones and have New Era clean the originals as they are much cheaper than the local guy.

YellowToy/A

iTrader: (1)

U should get good tuning software and a wide band that you can log in the software. I think you are going lean. You need to fix that.

1SLwLS1

iTrader: (6)

Both in queue. I've got a Dynojet Wideband on order as well as a fuel pressure gauge. I just need to figure out how I want to mount them. Id like to be able to have a gauge just for cylinder 7 as the wideband will give me an average of 1 bank.

As far as the tuning software goes, yea, that would be great but for now, I am just going to have to stick with Pat G doing my tuning.

1SLwLS1

iTrader: (6)

Just a little update, I have had no issues since Tuesday morning and I have been flogging the hell out of this engine in all conditions (once up to temp obviously). I did pick up some AC Delco wires that I will replacing the MSDs with tomorrow. Then I will go ahead and run the 3M kit for the hell of it and head out to the track. I will log each pass, if the software is cooperating.

I still plan on getting the injectors serviced, just not sure how soon that will be, it may be 2-4 weeks until I can find the time to either replace them and ship them out or drop them off locally.

1SLwLS1

iTrader: (6)

Update: I only got one pass at the track. Someone left their AC on and when I pulled up to tech in, he thought it was mine so he made me sit out for an hour and when I did get a run in, I screwed the pooch on the launch but they told me I couldn't run anymore until I got a helmet.

The car seemed a little down on power, but no popping, until about 2 weeks ago. Now, it seems to do this at even lower RPMs, sometimes just cruising at relatively high RPMs, maybe 2.5-3K waiting to pass, it will hesitate or hiccup for a second. But no matter what, as soon as I go WOT, bog, pop, bang! That got me thinking about a bad MAP or MAF or a huge undetected vacuum leak as IIRC (I'm not a tuning aficionado) the O2's are ignored on WOT during open loop and the computer uses the tables in the PCM to calculate AFR.

Well tonight I was driving to the corner store and just kind of slowly accelerating but holding gear and a revelation came to me. I thought I had noticed the interior lights dim a little one time when it was screwing up. I don't know why I hadn't thought about it before now, but I didn't. So the RPMs are climbing at about 1/2 throttle in 1st gear and when I reach a little north of 3.5K RPM, I notice the voltmeter just about plummet downward towards the red from a solid 13.5V. I am hoping this is my issue as the alternator was replaced about 3 or 4 months ago.

FYI, I had to put the AFR gauge on hold as my radiator decided to spring a leak and while I was replacing it with an LT1 unit, the AC tubing that runs from the top of the condenser decided to finally break and leak all of my freon. Since this is my DD, I had to fix it ASAP so the AFR gauge order was cancelled due to having to buy a vacuum pump and manifold kit plus a new line, freon, etc. I did, however, order a fuel pressure gauge, so I will be able to see if the fuel pressure drops during all of this if the alternator fix isn't the entire issue. I will keep this updated....

rich

What would cause the voltage to go into the red? The alt. Will keep it up at 13.5 -14 volts. But if the alt quits it shouldn't go into the red. It should drop to 12 ish volts. I think you have a really really big draw or a short happening. Something to pull the battery down that hard will be huge. At 8 - 9 volts it will break up just as you are describing.

1SLwLS1

iTrader: (6)

I misspoke on how I described it. It went into the yellow or hashes which is 12 volts. I swapped the alternator under warranty and now the hesitation isn't as bad, its back to intermittent occurrences and will continue to rev.

I still need to get the injectors checked and then move on to the coils. The fuel pressure is holding strong at 58-60 PSI. Since this is my DD, I may get a set of used coils prior to the injectors as I can get a set off of eBay for around $200 while the service to get the injectors cleaned is cheaper but will keep the car down for a day or two and to order a set of replacements is over $300.

rich

Also check the fp flowing. You can have pressure but no volume. I use clear tubing on the out side of the valve I open to flow into a gas can. I can see any airation in the fuel stream. Also you can have 0psi on the gauge and it shouldn't die out at idle. If it does die then a clogged filter or other restriction. Possible failing pump.

1SLwLS1

iTrader: (6)

I'll have to check that out too. I found a set of truck coils, brackets, and harness' for $100 on CL and I am going to pick those up tonight. I was actually looking for the LS1 coils because I didn't want to have to mess with fitting this on the valve covers and the clearance issues, but these are local and only $100 vs $200 on eBay. I will swap these tomorrow afternoon and post up results, if there are any.

I can tell you this issue is most likely heat related. I did a lot of freeway driving yesterday and the engine and oil were up to temp but the under hood temperatures were lower than usual due to highway speeds and I was beating the crap out of it and it was down on power but no hesitation at all. My thinking is the coils are overheating when the under hood temperatures rise and causing issues. We shall see though.