tiger18

iTrader: (1)

I was just reading a post a minute ago saying that when the vacume of a rotary engine falls bellow a certain amount its a good indication of low compression.......
so have a read and some one try give me a little info....


I rebuilt my engine about 8 months ago (did the following all new gaskets all new seals including ,side, corners and apex, rotor oil rings),,,havent put car back on road yet,,,but its developed a really weird and silly problem. i start the car up,,,the car starts straight up runs fine but strangely enough has a tiny misfire every 3 seconds (just a little pop and engine only slightly shakes)
When i leave the car running at idle ---after a certain amount of time say 10 mins sometimes 15 mins. the car has one of those misfires and floods out one rotor (by this i mean 1 min its fine the next its backfing down exaust and running on 1 rotor)
you get the drift,,,,,,,,,,
Now i can easily fix this buy pulling out the spark plugs (by the way is always front rotor) sure enough they are soaked in fuel... dry them out put them back in,,,and it fires straight back up running fine.
Now this is where it gets weird,,,,it never floods a second time,,car runs ok now,,,can drive it and it never floods out again. until its parked up and left for a few days again.
Now i was wondering weather engine was in some way not holding good compression.. but i did a vacume check and i get 18.5 (which as i read is pretty good) so id say compression is good (also did compression check and it reads good all rotors all faces)
so now im thinking,,,
1) dodgy spark plug
2) dodgy ignition lead
3) faulty injector
4) i have no idea,,,,, maybe faulty ignition coil???
any ideas guys,,,feel free to ask more detailed questions..
thankyou

EKTwin93

I doubt it's an ignition problem. If the engine is flooding out a rotor there must be a lot of fuel. I weak fire on a plug shouldn't cause any more than misfiring or stuttering/stumbling. But, you should check your coil pack, check the ground on the coil pack, and check the wiring to the connectors onto the coil pack. To be honest I have no idea what problem with the fuel system would cause a rotor to completely flood out though, maybe a bad fuel pump relay, bad FPR or perhaps the vacuum line popped off the FPR. However, this happened in my car, and it just flooded at start ups and backfired horribly while driving. But, maybe the combination of a weak spark and a the line popped off your FPR is enough to flood it. Sorry I couldn't help more. Hopefully some of the geniouses will chime in and help, sounds like quite a problem. Good luck, Evan

J.S.J

I guess you could just take a compression reading. That would surely give you an answer to the mechanical end. One could theorize conductions within the front rotor which when cold could lead to a richening conduction that leads to a fouling. Once there is enough heat generated or other conductions related to heat keep it lit. I might see what the compression is and if thats OK I might look at your plug wires/plugs (Plug gap) since its a waist spark system make sure the other wire is good. The system uses the off plug wire as a ground so to speak. If that looks OK surely make sure there is no vacuum leaks. A vacuum leak effecting the rear rotor would throw off the map sensor overall but it might just lean the rear rotor enough to keep it from fouling. I also would wonder about the front injector, volume and or spray pattern. Yes indeed we do agree this is an odd one. For the most part letting your engine idle for 10/15 minutes just might not be something to do. These engines are more of less high performance designs and I would think they don't like to idle like a Toyota might for long periods of time in general. Thinking as I go here you might look at the fuel pressure regulator. Make sure its not leaking fuel past the internal seals up the vacuum line. Idle would the time it would hurt the most. John St John

cruiser

You must have disconnected a vacuum hose - like MAP sensor hose

tiger18

iTrader: (1)

ok thanks guys.....ive got new ignition leads and new spark plugs comming in the next few days,,,if that doesnt work,,im gonna have injectors removed tested and cleaned,,, then im gonna source a spair set of coil packs,,,
the other things thats really weird is once ive dried out the spark plugs,,,ive noticed that when i fire up the car,,,,it runs perfect for 30 seconds (no misfire or little pops at all). then after that time it runs in the usual manner with an odd very tiny misfire aver 3 seconds...
which leads me to think a fuel problem

Howard Coleman

iTrader: (6)

primary fuel injector leaking IMO

howard coleman

tiger18

iTrader: (1)

yer i was thinking primary injection leak,,,,would have to be primary to be only doing on idle.. gonna get all four out and have them cleaned and tested....or may just buy 1 new one for the front.