looking for help for 84 riviera t-type(3.8sfiturbo)bought carw/ bad motor.previus owner stated started running bad and black smoke mechanic replaced maf (rebuilt)&O2 sensor,said engine had turned a rod bearing,and needed ecm(said caused gas flooding which diluted oil contributing to rod bearing failure) towed car home,rebuilt entire motor and replaced ecm w/ autozone reman unit. started car,broke in cam, seemed to idle fairly decent. when i began to drive the engine would not acellerate at anything more than 10-15% of throttle,just wont take the gas. checked fuel pressure- ok, obtained scan tool to check tps and maf seem to be ok. tried a different ignition module(brand new GM found behind seat) and a new coil pack same problem runs extremely rich and fouls plugs quickly. also checked tw sensor, removed fuel tank and had professionaly cleaned(thought problem maybe contaminated fuel) when engine is revved in neutral cuts out badly around2500 rpm,strong fuel odor in exhaust and only codes from ecm is rich exhaust(45 if i remember correctly) I have heard that rebuilt maf's are natorius for giving problems so i put in a new set of plugs and hooked up scanner to look at maf readings. at idle semms to be between 12&15 gms, test drove and readings seems to be high for engine speed & load(70-80gms when engine begins to cut out badly)I am trying to make a comparrison based on readings i am seeing on my 87 GN w/ scanmaster on dash. could this be my problem, or possibly a bad prom(ecm did not come w/ ,reuse existing) I am currently searching for a known good maf. Looking for anny suggestions maybe i'm not looking in right area for problem. only warning light on dash is alt/bat light,plan on gettingnew alt( battery is fully charged).Thanks for any help, Tim Maywalt
Well, the only thing that I can think of right now is that my car reads 5-6 maybe sometimes 7 gps on the MAF, I would think that maybe your rebuilt isn't that good, or isn't the right one. Also, make sure you have a good ground. I had one in my GN that was reading a little high once. Can't remember exactly what, but a replacement one wouldn't help. It turned out the sensor was not grounded. The readings would even change when when you brought the rpms up, but it had a rough idle, and even worse, wouldn't run good at all when you rev'd it. I would start there, since I can't think of anything else. Good Luck,a nd keep us posted.
Brian
sorry i couldn't get back to the sight sooner. i checked the ground coming from maf sensor continuity checked ok and wiggled wire no signs of trouble there. i found some info in a GM service manual about setting the cam sensor (dot on cam drive facing pass side and window at top facing drivers) so i reset cam sensor using method from service manual but still having same problem. located "known good "
maf and coil/module assy on turbo trader and are waiting for arrival. i saw on another discussion a guestion regarding the pulser wheel on back of balancer for crank sensor maybe it has walked and is out of time or phase. is this a common problem and does anybody knows the symptoms this would cause? i may look in this direction soon if maf does not fix problem (found a nice diagram of relationship of cutouts and keyway in GM manual) thanks for any help
It's not really common to have the interrupter ring "move" enough on the balancer to cause the problems you describe. Not saying it can't happen, but it'd be pretty rare.
Also, clean the interrupter ring and the crank sensor REALLY well. If there's a little metallic debris on it, it can cause all sorts of havoc.
received used maf today and installed, car runs remarkedly better even with gas fouled plugs. i couldn't tell you where this guy got this replacement maf but doesn't even look similar to original. size of body looks like it came off a 4 cyl or something and has caused me all kinds of headaches and grief. thanks for you guys help and i am goin to keep working on finishing up car.