97lE383Z

Well guys I'm stuck between a rock and a hard place here. My best friend/mechanic just passed away. We've been building this thing since 2009. Anyways got the engine in finialy awhile back and got tunedup by PCM performance. And the thing idles now on its own. When reved it starts to load up heavy and POP a lot. It will run up and down the road now. I don't no if my cam ain't timed right or what. Pretty lost here obviously. Im sellin it no mater what. Would like to get it running better first; or entertain offers as is. All the supporting Bolton's. Got stock M6 And 3:42 s 592 592 cam from bullet cams. Le3 heads .le ported intake 383 rotating assembly light weight crank. Runnin 91 octane. Any 1 with prior experience in dealing with such a problem you're input would be highly appreciated. Thanks!

Huntr1117

Might want to post a few more details about the setup. Are you still running an opti, or possibly a 24x? Any burnt plug wires? O2 sensors new or used? Did you buy 02 extensions or make your own? Are any or those wires burnt. Just a few things that may help troubleshoot.

97lE383Z

Yes new gm performance opti. New 02s. New extenstions .Only have the two 02s the long tubes Custom 3inch xpipe exhaust new 37# Delphi injectors and new graneteli fuel pump. I am not rich by now means. I come into alil money in 2009. Decided to overkill the build. Wished I'd gone with a nice Lil mild 350 cam and heads package now. No burns in wires or extentions. BTW I'm blessed to have aknovaman from pcmperformance live down the road from my dad and he has been nothing but great to me in workin with this car

Injuneer

What year is the engine? What year is the PCM? The year of the engine can affect what goes wrong with the Opti install (unvented vs vented drive system). You could have problems ranging from incorrect timing chain install, incorrect Opti indexing, crossed plug wires, faulty O2 sensors, bad exhaust leaks, incorrectly adjusted valves, excessive fuel pressure, etc.

The more info you can provide about the engine mods, like the full cam specs, not just the lift, and a description of exaclty how it starts and runs (misfires, surging????) the more likely we can help. What do the plugs look like when you pull them? Does it smell like its running excessively rich?

97lE383Z

Hey now guy I think you're on to something. I've checked all the basics. But you bring up a very great new possible problem to examine. Block is a 1994 out of a Cadillac. PCM is 1997 as far as the timing chain I ordered I think I screwep up and put one for a 97 model. Im forsure that i put on an opti for model years 96-97. I do apologize for my vauge info!! 240/248 on 112 LSA Last time I tinkered with it was at 9months back. Go in to put gas in her and start again on Saturday. Getting married and buy in a house. Need extra funds and my best bud left me his 96 Z which has its own set of pproblems; but that's for a different day... I no we turned fuel pressure up and down and the lower the better it ran. It does have a couple exhaust leaks. You can rule out plug wires crossed and bad o2s, excessive fuel pressure slim chance valves aren't adjusted just right. It starts up and once o2s warm up and go into the loop deal (open or closed can't member which 1 is warmed up) then it idles smooth at 1200 rpms. It wouldn't maintain idle at 800 to 1150. Rev it up in neutral and its smooth on the way up but on the way back down it cracks and pops real loud. Slight smell of gas not reaal strong. Changed plugs and made no difference. Under a load it really struggles to move. You go to much on the foot feed and it really loads up and strugles . You would never no the potential of that motor by how sluggish it is. Anything else I'd be glad to tell ya. Thanks for the reply!

Chimera96

you need to resolve (fix) your exhaust leaks if pre-02's. The PCM will read more air and then dump fuel making it run rich if leaks are pre 02's

fuel pressure, what is it?

should be 37-42 with vac

you have a big cam so there may be compromises in how it runs on the street but assuming all "mechanical" issues are correct a good tune should get it to not run so rich and run correctly

I assume your tuner has confirmed your PCM compatibility with your motor

97lE383Z

Hi there. Leak is post 02s. A poorly assembled x pipe system from previous owner. Was planning on building my own like my buds 3inch summit x and bullet mufflers once I got it running decent. But sinc that could be causin my troubles I may take his off and stick on mine but I doubt thats the jist of things. I'll havta put the gage on this weekend. Hi 30s I can say forsure on the fuel pressure. I don't think theres any problems with 94 lt1 block matched with a 97 pcm. ? Or maybe I'm wrong.

Injuneer

Exhaust leaks after the O2 sensors do not affect anything.

Have you scanned it for codes? Very easy with the OBD-2 PCM.

You mention adjusting the fuel pressure. What brand is the AFPR? Make sure you set it back to 43.5psi at idle, with the vacuum line off the regulator.

The 94 Fleetwood engine does not have a crank position sensor for misfire detection. How did you address the deletion in the 97 PCM?

While the 94 F-Body's had the unvented Opti, I think the big car LT1's (SS/Roadmaster/Fleetwood) got the vented Opti in 1994.

That cam is fairly large (assuming you are quoting the duration at 0.050" lift), and is going to be difficult to tune.

97lE383Z

Hey thankya kindly for the info! I got a crapy accel regulator i got for free from my buddy. He has a holley i could switch out if needed. Well I got my to do list for tomorrow 1. Set psi back to 43.5. 2. Scan the codes (its been awhile and don't remember off top of my head). 3.verify which opti unit is in there currently. 4. Contact tuner to find out about his method for deltetin crank postion sensor or if he did it. I no that I went to large on the can for my application. Ponderin a switch from that big custon cam to a common shelf cam; such as a cc306 or gm847... I'll post asap when I have some answers. Thanks

97lE383Z

I talked to my tuner. And he said that it depends on which timing cover you use... 7856081342. Anthony said feel free to call him because he can obviously tell ya a lot more use full info than I.

Injuneer

The 1997 PCM requires a crank position (CKP) sensor input. It is only used for misfire detection, so you can "tune it out". The 94 Fleetwood engine does not have a CKP sensor. So the tuner had to do something.

I'm full aware of the differences in the timing covers: Here's a picture so you know the differences.



If he changed the timing cover and installed a CKP, and changed to the shorter damper hub (provides room for the CKP reluctor), it's possible that he simply connected a CKP sensor. Point I'm trying to make here is that there are issues that need to be addressed when you mix & match engine year and PCM year. If these issues aren't addressed, you may have problems.

Another possible mix & match problem - which knock sensor is being used? The 96/97 PCM requires a 100kOhm knock sensor. The 93-95 F-Body LT1 uses a 4.5kOhm sensor. The Fleetwood engine has 2 knock sensors if I recall correctly - and I have no idea which sensor they used. Has this been addressed? If it wasn't you would be getting a code for the knock sensor. You didn't answer the question - has it been scanned for codes?

97lE383Z

Gettin my deceased friends solus pro tomorrow..... just hopin i can work it. i loaned my simpler craftsman out and guys out of town I talked to my tuner He said everything is 97... Its all been changed over for 97. We put all the accessories etc from my 97 fbody engine on the 94 block when it came back from machinist. So im sure that it has been addressed. Turned fuel pressure up today. She fires right up i mean no problem I think the large cam is alot of my troubles. But then again something is causin it to load up heavy. Wonderin about tryin to sell AS IS. Maybe 5k. Ready to cut my loses and move on. Im no lt1 performance guru like my dead best pal was.

97lE383Z

Well sir you are on point with the crankshaft postion sensor . im throwin 1 code po 336 crankshaft postion sensor A circuit range performance

97lE383Z

I found that crank postion sensor has no affect on engine performance. just letting me no of an engine misfire... So where would I go about finding the misfire? Would I be right to assume the misfire is from the timing bein off?

Injuneer

Misfire can be from:

SPARK - worn, fouled, cracked, loose, defective plug; burned wire; coil arcing to ground, weak coil, faulty ICM, faulty cap/rotor, plug wires crossed (wrong cylinder), Opti drive indexed incorrectly..

FUEL - running excessively rich, excessively lean, leaking injector, plugged injector, defective injector, faulty injector wiring.

COMPRESSION (and valve train related issues) - low compression, burned valve, sticky valve, faulty lifter, worn cam lobe.

A lot more but that's all I can think of at the moment.

If they had installed the cam position sensor and it was working, the PCM would set a code telling you if it was a random misfire, or specific cylinder(s) misfire, and provide the misfire count by individual cylinder.

Start by opening the hood up when it's dark, and looking for arcing on wires, coil and distributor. It's hard to see all the wires with them tucked under the manifolds, but it's worth looking.