eastcoastrotary

iTrader: (5)

I'm looking for some help. I just bought an 89 gxl. The previous owner said he was using it and parked it before our first big snow here in Jersey and after the storm he couldn't get it started. He then said he kept trying and finally two weeks later he got it running again but was getting a hesitation at high rpm's, he said like 7k. He brought it to his "non-rotary" mechanic and they changer the TPS and couldn't get it started since and gave up. I got it home,found the compression is great, it's pumping fuel to rails, but no spark or fuel in the motor. The guy had changed the plugs but had leaders in all holes. I since corrected that. I checked all fuses under the dash and under hood, all are intact. The ones under the hood don't look to hot but are intact. I checked the main relay and it switches fine. Also checked the continuity and also fine. Tried disconnecting AFM and bought another CAS and connected it and spun the bottom gear,no clicking or spark from plugs when placed on the intake plenum. Will the pressure sensor also cut spark and injectors? I was gonna check that next. Also where is the ECU located so I can check those grounds. I'm getting pretty frustrated with all these electronics. I'm used to 12A and they never let me know. PLEASE HELP! Thanks

RotaryRocket88

iTrader: (7)

The ECU is under the carpet on the passenger side.

Checked all fuses with a multimeter rather than just by eye?

I would normally expect the CAS to be the problem here, but trying another one doesn't make it seem likely. You said there was no audible injector clicking, but have you tried pressurizing the rail w/ the fuel pump test connector jumped? Put the ignition in the 'ON' position, and spin the CAS by hand. The primary injectors should fire, and having the rail detached from the block will make it obvious. It's something I would rule out before moving on. You can also test CAS output per the FSM.

The AFM can't cut spark, but it can cut fuel.
The pressure sensor can't cut spark or fuel, but it affects mixture.

eastcoastrotary

iTrader: (5)

No I didn't check the fuses with a voltmeter. teh ones under the dash i guess i can just touch the top of each side and check for continuity. The ones under the hood i guess i would just have to pull and do the same. I was gonna replace all the ones under the hood anyway cause they look pretty old and crappy. As far as checking the CAS, i didn't see anywhere in the FSM to check it but i did do the continuity test per the haynes manual and that checked out fine. But also like i said i had connected another CAS i purchashed used and still had no clicking or spark when i spun the bottoe gear in either direction. I'm getting fuel from the pump because i pulled the return line and cranked and got tons of fuel but when i pulled the plugs they're dry as can be.

eastcoastrotary

iTrader: (5)

I got to mess with the car this weekend and all fuses were good. I spent all day regrounding just about everything I could. I also dissassembled the fuse block, cleaned all connectors, replaced all loop connectors, got evrything back together and still no spark or injector tick when spinning CAS wheel. I got frustrated and started to look by the ECU. The top bolts were off and it was just held by the bottom bolts. Also the biggest clip on the left, 4 wire on the bottom counting bottom right to left was a red wire, it was spliced with a red and green wire.....is it supposed to be like that? Also does the mounting bracket help ground it? I pulled the ECU and brought it to my bench to inspect it. I open the covers and saw what seemed to be some pretty serious black burnage on some of the contacts. After really opening it I saw what seemed to be a big resistor or chip like cracked and sort of melted looking. Also the were 2 small resistors that are located behind that that also looked smoked. Si I'm gonna assume I need a new ECU. My question is, why might the ECU have fried like that? The car cranks, gets fuel, lights and other stuff work. Could it really be fried? The grounds I found were in pretty bad shape. I'm just concerned that if I put another ECU, I might fry it too. Also what is the MOP and how can that fry your ECU? Thanks all for the help.

millennm

iTrader: (6)

MOP is a metering oil pump. It pumps a small amount of engine oil from the oil pan into the intake manifold. The oil goes into the combustion chamber to lubricate the apex seals.
I'd pull the whole wiring harness out. Then continuity test every wire between the ECU and engine bay plugs. Disconnect the harness from the ECU and feed it through the fire wall. Just take alot of pictures. You'll need them when you're plugging everything back in.

eastcoastrotary

iTrader: (5)

My ECU was fried and it was due to the omp...got a "new" used ECU and disconnected the omp and it fired right up.....I believe it is in limp mode though..correct me if i'm wrong but if i whack the throttle it will almost cut out but if i slowly press it, it will excelerate all the way but again under heavy load it seems to backfire and want to cut off.....shout out to JReed who drove all the way from PA to deliver the ECU and a alternator I needed......

RotaryRocket88

iTrader: (7)

Yes, you're going into limp mode with the OMP/MOP disconnected. Whatever you do, do not plug it back in, or you'll fry the new ECU too. You've got a couple options here: replace the MOP or re-chip the ECU and premix. Pocketlogger offers a MOP removal option now: http://www.pocketlogger.com/index.ph...age=1&ecu=S5NA.

LikeThunda

iTrader: (1)

had a similar issue..... my OMP was bad so my car went into LImp mode..my ECu wouldnt shoot any codes so i Replaced OMP and ECU.. and Reset the Code it was shooting out after ECu replacement... after that it worked just fine.


(2 rx7's with LImp MOde Issues.. Both resolved doing the above ^^^)