HELP! Engine Issue, can't diagnose!

[93formulalt1]

FWIW, while I have never done this personally while an engine was still in a car, you shouldn't have to completely drop the pan to do a timing set. You can just lower the front of the pan enough to get the timing cover in & out.

Yeah, I was going by what the Haynes manual said. After further research, the best way to do it is to swap the 4 corner bolts in the pan with timing cover bolts (1/2" longer than pan bolts) and let it drop about 3/4" to get everything to seal after reinstalling the timing cover. The oil pan gasket is a 1-piece, so it shouldn't need to be replaced, it's less than a year old (replaced the oil pan in September of last year).


If you guys aren't convinced it's the timing chain, toss some ideas out there. As long as they aren't super-expensive to test/repair, I'm more than willing to entertain them. When I go home in a couple weeks, I plan to hunt down my LT4 knock module and swap that in, see if it makes a difference. If anyone is willing to drive out to where I'm at (Union Pier, MI) to check it out, you are more than welcome to do so. Any and all help is appreciated.

[93formulalt1]

What codes are you getting? To bad you can't put freeze frame up so we can see some data on it.

I'm not convinced timing chain.

No codes. I'm working on getting my hands on a cable to run a datalog and pull the tune off the PCM for additional diagnostic help. Only limitation is my laptop, which has no serial port, and is running Windows 8. I don't have another computer available to me currently. I would need software that's compatible with Win8 and a USB ALDL cable.

[JoeliusZ28]

definitely shouldnt need to drop the pan... Not a terrible job at all imo.

[93formulalt1]

definitely shouldnt need to drop the pan... Not a terrible job at all imo.

I've got lots of little birdies between here and LTXTech telling me it's NOT the timing chain, and that I should do this, that, and the other before considering it. I'm completely lost at this point, I have about 30 people telling me what's wrong with the car, some telling me I should listen to the mechanic, others telling me the mechanic doesn't know what they are talking about, and still more saying I'm wasting my money by not doing X or by doing Y. I'm being pulled in a hundred directions, can't seem to find the answer, and I don't have the time or money to continue messing around with this. I'm frustrated, broke, and my car is parked.

I leaned toward a sensor issue, because the car seemed to run alright in open loop. Come to find out, I had one bad O2 sensor, and my MAF readings are higher than they should be. Unplugged MAF, no change. Replaced O2's, no change. Only other sensor I can think of that would cause this is a knock sensor. Aside from that, if it's not the timing chain, the only other issue I can think of is a PCM/Tuning issue. I'll get a cable, datalog, and upload for you all to look at. I'm not good enough at interpreting the data contained in there to make an accurate diagnosis, but I know a few folks here are.


If this would have happened 10 years ago, back when I had dial-up internet and even less money than I have now, I'd have been up the creek. lol

[JoeliusZ28]

Pulling the timing cover and inspecting doesnt cost you a dollar unless youre paying someone else to do it

[93formulalt1]

Pulling the timing cover and inspecting doesnt cost you a dollar unless youre paying someone else to do it

Can't do it until I go back home to pick up my tools, unless I only need a 7/8" box-end wrench or flathead screwdriver. . . All of my tools are in Belleville. Won't be back that way until the weekend after next. And I've been told I can inspect by pulling the Opti, turning the crank by hand, and checking how much movement there is before the opti spline drive moves. . . I'm going to pull the timing cover when I take the car back home, since I can put it up on the neighbor's hoist to do so.

I'm ordering an ALDL cable to datalog, I can't find mine, but I found a Moates cable on LS1Tech for $50, so I'm going to go ahead and pick that up.