EFIDynoTuning Forum

Update: It looks like the secondary chain tensioner had a bolt back out and it came loose. The secondary chain broke. Good news is the cams are not seized. Now i need to pull the valve cover all the way off and get final assessment.

Im afraid that one of the cams locked up and broke the secondary chain. I hope thats not the case.

Decipha can this do lot a damage to the valve train or engine? when you say came loose are you referring to the bolt that holds the sprocket on the cam? And I also want to note that the oil pressure was perfect and coolant temp was perfect the entire time and the engine never made any rattling noises other than the noise i noted above.

Im working with a 2003 Mach 1 that has a rebuilt 97 mark viii short block, 04 aviator heads, 01 cobra intake cams and long tube headers. Everything else is stock. I reused the mark viii timing chains, guides, metal ratchet style tensioners and sprockets because they had less than 19000 miles on them. Ive put a little over a hundred miles on the car so far. Last night when i started it i noticed that it had a very slight shutter or miss. I thought that maybe it was the plugs since ive been doing some tuning on the car that maybe they were slightly fouled. So against my better judgement I drove my kid to practice and it ran good other than the stalling issue ive been dealing with. Driving home in 4th gear between 2-2700rpm the wideband would go from rich to lean and the engine would rev up and down following the afr. And then i heard a weird "whooshing?" noise come from the engine and it lost power and started misfiring extremely bad. I managed to limp it home and pulled the coils and the checked the plugs to make sure it didnt blow a spark plug out. All the plugs were tight. It struggled to start back up but finally did, and then I noticed a weird metallic rubbing/clanking sound coming from the front side of the driver head. The sound was not very loud and kinda faint. It almost sounded like it was coming from the chain that ties the two cams together. Its gonna be a few days before i can work on it again. Anybody have any ideas of what i should look for or what it might be?

One last thing, I have a 90mm lightning maf on the shelf. Would be worth it to install or just stay with the stocker?

not sure how accurate the HP and TQ logging is but it has my car at a little over 300hp and around 290tq. the tq curve is nice and flat!

Should take 4* out of the entire timing table to run 87? im running 93 now with the stock table have zero detonation that i can hear. i plan on finding the knock sensor harness before summer and re-enable the knock sensor hardware.

My bad i thought i had my signature updated with the current engine specs. My car has a stock 97 mark viii short block with 04 9 thread heads, longtube headers and 01 cobra intake cams. everything else is stock per 03 mach 1.

Is there any benefit to ramping the timing in any faster or at a lower rpm than the factory table? So far during my WOT pulls im only getting to 20-25* of timing at top of the rpm range. So basically im averaging around 15* of timing throughout the pull until the last 500-1000 rpm. Im not mod motor guy so the timing tuning aspect is new to me. on my 5.0 pushrod engine im at total timing around 3200rpm.

Ok, Thanks again