Electronic Nightmare..bad cam sensor?

89ohmy

Registered User
I've been a member of the sccoa for quite a while and ive had my first sc for a little over a year now. I bought it knowing what i was getting into and in may this year the motor went thanks to a dyno day...anyway i bought a rebuilt motor from someone in riverdale, nj. So i have the motor in and ive passed the 400 mile mark but I know theres something wrong with it electronically speaking, I preloaded the lifters your way and that worked fantastically.

The problem I'm having is that its hard to start (it turns over too much and wont start unless I hold the gas) and it idles really rough and then its like something clicks and decides to be okay like 2 cylinders started to fire then it idles at 1000 but it feels okay. It seems as it has no power and every so often (I'd say one in three times) when i let off the gas after i start moving and going through the gears it backfires out the exhaust.

Its got new plugs, wires, a known working DIS module, a working crank sensor, accel coilpack and accel 8.8 wires. the ecu is out of my other 89 which i drove with no problems.

The car has an 85mm tb, ported heads, ported intake,
255 lph bbk pump, and longer pushrods (due to a reground cam) they're 7.2" long. any help is appreciated!

Thanks for your time, Zach
 
i know that the timing chain itself is right on and the cam sensor is timed the way it should be, ill try moving it a little though to see if that helps at all.
 
The problem I'm having is that its hard to start (it turns over too much and wont start unless I hold the gas) and it idles really rough and then its like something clicks and decides to be okay

Overly rich condition. Either the swapped computer could be at issue, issues with fuel pressure regulator, or problems with the mass airflow sensor. Holding the gas to the floor tells the computer your engine is flooded and causes it to hold back fueling. As it cranks after being flooded with no fuel a couple cylinders clear enough to fire, which gets the engine running, eventually the other cylinders clear and it smooths out. (thanks to double platinum plugs which are harder to fuel foul)

Is your check engine light working, and is not not on indicating that it has stored some codes?

You have a 85mmtb, but didn't say what your MAF is. I expect that fueling is out of wack due to your maf, and your car is throwing a code for o2 sensor out of range, rich.
 
Overly rich condition. Either the swapped computer could be at issue, issues with fuel pressure regulator, or problems with the mass airflow sensor. Holding the gas to the floor tells the computer your engine is flooded and causes it to hold back fueling. As it cranks after being flooded with no fuel a couple cylinders clear enough to fire, which gets the engine running, eventually the other cylinders clear and it smooths out. (thanks to double platinum plugs which are harder to fuel foul)

Is your check engine light working, and is not not on indicating that it has stored some codes?

You have a 85mmtb, but didn't say what your MAF is. I expect that fueling is out of wack due to your maf, and your car is throwing a code for o2 sensor out of range, rich.

I completely agree. I was also going to mention if the firing order was correct as most of the repair manuals have it wrong. That will also cause starting issues and throw unburnt fuel out the exhaust.
 
The firing order is correct i made sure of that, i know a lot of places have it listed wrong, ill see if turning the cam sensor but i swapped my computers in both of my 89s and the one with the stock motor and all is fine so idk
 
I know this is an old thread, but I'm having the same problem with my freshly built motor. I have a lot of upgrades and am having a hard time getting it to run. The SCP exhaust doesn't fit so it's open after the headers. Did you find your problem? I'm thinking the open exhaust is causing a problem.
 
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