Hi everyone, this is my first post here, wish I had found this forum months ago!!:mad:
Anyhoo, I have a \'88 FC non-turbo and I lost compression on the rear rotor some months ago and have stripped the engine down and found a broken apex seal. The car has been back together nearly three months now but I cannot get her running properly!
Its a pig to start, mostly just flooding, but when it does start it runs very rough and lumpy at low rpm, wont idle at all. Seems fine at 3k and above.
I\'m sure its the rear rotor thats the problem still. I can start it and run on the front rotor alone fairly well, but not the other way around. There\'s fuel, there\'s sparks and they are at the right time.
I\'m worried that I have broken something during the rebuild, a vacuun pipe or wire.
Any suggestions? how to dianose the problem??
TIA
I had the same probs and all it turned out to be was a hole in the air intake pipe, because it was after the airflow meter it made it run sick as a pig on idle and eventually stall but when it was being revved it seemed fine
thanks for the suggestion, I\'ve checked it and its ok.
Besides it wouldn\'t explain the difference between front and rear rotors. I\'m trying to think of some way air could leak in to one rotor only
I would do a compression check. What you are describing sounds very much how my engine behaved BEFORE its rebuild.
At least it would remove 1 possibility
Bill
QuoteOriginally posted by bill shurvinton
I would do a compression check. What you are describing sounds very much how my engine behaved BEFORE its rebuild.
At least it would remove 1 possibility
Bill
This is the best advice! This is why my engine is sat on my patio waiting for Pip to come pick it up for me, and that I have to cycle to work at midnight in the pissing rain!!!! But I refuse to sell her cause I know that it will all be worth while in the end:cool
is it possible to check the compression without resorting to that very flash and expensive test kit that the dealers would use?
What sorta rx you got sean?
Hi Barry,
You can use a piston engine comp. tester - but the readings won\'t be accurate.
What you will be looking for is that the comp. is the same/similar per chamber for the front and rear rotors.
Just take the two top (trailing) plugs out.
You can also do a test by ear, by taking the two trailing plugs out - disconnecting the coils and turn it over. They should all sound consistent i.e. psh psh psh psh psh psh
What was replaced in the engine? was the rotor housing damaged and then replaced after the original apex seal let go?
Hi Glenn,
Thanks for the reply, I have checked the compression by ear as you described and there is no discernable difference in the sound from the two rotors.
All the apex and side seals were replaced on the rear rotor, the housing was NOT replaced, there is some marking where bits of broken apex seal impacted but after discussion with the main man at Hurley engineering (and due to not having the cash for a replacement) it was considered that the effects ot the scoring/pitting would be negligable. None of the damage was on the compression/combustion part of the housing.
I know this is not an ideal situation, but after spending nearly £4.5k in the last three years on exhaust and engine I\'m not able to put much more money into the car.
The more I look into what is wrong the more I\'m convinced its not the engine internals. However, I appeciate people going over all possibilities to ensure I haven\'t overlooked something.
Barry
Possibly a damaged ecu?
Have you changed your plugs/leads?
Proper connections for wiring? (ie. wires leading to/from the engine, when you removed/installed it).
Intake isnt blocked with anything? (airbox)...
injectors are clogged/damaged?
Those are just generic things which could be the problem....
Hi
damaged ecu? difficult to tell without a known working one to swap it with to see.
plugs and leads are not new but have all been checked out
there is a spark at each plug
I took lots of pictures with a digital camera during disassembly to help when it came to reassembly to ensure I got the wiring and plumbing right
injectors have all been checked and function ok, the wiring has been checked back to the ecu
btw, which injectors supply fuel when idling?
It may be an air block but it must be specific to the rear rotor because the engine will run on the front one but not the rear.
Barry
Don\'t they only have 2 injectors :confused:
One in each chamber? (im a rotary newbie... more of a piston man :D)
I used a regular compression tester on my engine and was pleased to note that my readings were close enough to those from a factory tester to at least prove the engine was not right.
A compression test is only #15-20 at a specialists, so worth doing. If you have put new seals on an old housing it is likely to idle like a dog for the first few hundred miles anyway.
Get that checked. I spent 3 months trying to trace a fuel, spark or air leak problem and it was a worn engine all along. You have rebuilt that part so that is the first thing you have to prove is right
Other than that you have to just check every connection to see if there is an air leak.
Bill
Wobbz,
They have four injectors, two per rotor. They inject fuel into the inlet manifold, one right in the inlet port and one further up the manifold.
Barry
Ahhh thats right.... my brothers mate runs like the standard injectors and 2x bosch (?) 1600cc items :D
~350rwhp @ 15 psi... (from what they tell me).... fully built engine from R-Magic... HKS to4r.... its a very nice ride... too bad I haven\'t been in it yet :mad:
Barry,
I have checked a engine by ear before and it sounded fine, when I put my hand down by the plug hole, I could feel that it only had one strong pulse, this engine had chipped a apex seal, which is now running really well on used housings(owner was on a budget).
Jason
you\'re right, no compression on rear rotor:(
looks like an apex seal not working, I get one weak pulse in three instead of three strong pulses.
Barry, deeply depressed
Barry,
It is possible that one seal is slightly jammed in the rotor (did you clearance them correctly? - as per the manual?).
You may be lucky in that it is stuck (sometimes they can even carbon-up and stick - ulikely as your engine is new).
You could try unsticking it (if it is stuck) by taking a leading plug out, get a torch, a mirror, and a small blunt instrument - turn the engine over until you see each seal and prod it in and out.
The best way is doing this through the exhaust port (but then you have to take turbo off etc.).
It may be possible that after running for a while it will all settle in.
Let us know how you get on.
.ps Nice one JayDee - I\'ll remember that one.
Why not use my technique, that I use on my computer when it doesn\'t work?
It\'s called BBT.... "Baseball Bat Therapy"... hahaha... i\'m sure you get the picture :D
Note: I do not recommend you actually baseball your car :D
LOL!
I might just try that, not for the cars benifit but mine!:rollin
Barry
Glenn
No I must admit I neglected to clearance the seals, I just checked them for free movement in their slots.
I have now made sure all the seals move in and out through the plug hole, they did, still no compression.
Which is the puzzling thing, virtually NO compression, not even one good compression stroke. That would require at least two seal to not be making. What else could cause a loss of compression on all three rotor faces?
Barry, stumped
Is it possible that the sides of the housings (walls?) are not secure properly? thus any air which is to be compressed just goes out a tiny gap?
Im a noobie to this stuff.. please dont flame me if my idea is stupid :)
Maybe you have left some side seals out or springs or some thing silly like that.Have you got anything left lying around?
Kind regards
Carl
It could also be the corner seals, being to tight and stuck, I always find these need work doing to them to move smoothly
jason
Gawd!
Your quite right Carl, there are three side seals lurking in the bottom of the box I kept all the bits in.
I cant believe I\'ve been so stupid:(
Amateurs eh?
Now I have to go through all the nause of scrounging the tools and stuff to get the engine out again. It took me nearly six months over this summer to get it done first time. God knows how long it will take this time of the year.
I\'m getting married in november, was hoping to go away on honeymoon in the car. Dont think thats going to happen now.
Thanks to everyone for your help and input.
Barry
You can do it mate!
Rip that little sucker out :D
It shouldn\'t be too hard... hell, my brother pulled out his 2jz (from his supra) in a day or 2... (and he had to remove radiators etc... ie. more stuff than the RX7\'s... as they block the engine)...
:)
Sure, putting it back in is the hard part, but give it a go :)
Hi again,
Ok the engine is back out and sure enough no side seals on one side of the rear rotor. Doh!
However when I put one of the seals in I noticed that there were no springs in the slots!
And there is no trace of them in the box that I was using to keep all the bits. I\'ve looked high and low in the garage and they are just not there!
Could the engine have eaten them when it was run with out side seals fitted?
Any road up, the short of it is I need three side seal springs.
Anyone got any?
Barry
Hi Barry,
if you pm me with your address I\'ll send you some secondhand ones.
Kind regards
Carl
Carl
pm done
thanks, you\'re a star!
Barry (soon be rotatin\' again!)
On ya Barry - check out the online manuals also at:
//www.iluvmyrx7.com (the factory workshop manuals are there).
Hi again,
After a much longer interval than hoped, the car is all rebuilt!
The engine starts readily but wont idle.
If I hold the revs up with the throttle and slowly back off, everything is fine until the revs drop below 1500, then at 1000 rpm it starts hunting between 1000-1500.
Dies as soon as I take my foot off the peddle.
any ideas chaps??
poor compression, still?
air leak on the inlet side somewhere?
or just needs setting up?
Barry
Hi Barry.
Well done on doing all that work and getting this far. It is unfortunately, very easy to make a mistake like that. I once out the clutch plate in my wifes 323 the wrong way round, even though the plate had BIG red writing on it, saying "Gearbox side". DOH!
I dont know what your current problem is, but at least its a different symptom now.
It could be air leaking in somewhere.
i had a similar problem with my EGI - it would run fine but hunt at low revs - found out that i hadnt put the oil cap back on DOH ! :)
sean has a similar problem ( i think ) try PM\'ing him and see what he thinks
Sounds like an air issue some where, one of the inlet gaskets? I think the BACV on the FD will give similar symptons if not working properly maybe??
Hi guys and thanks for the replies so far,
Done a few checks,
can rule out compression as a problem, both rotors seem to give good results,
did a resistance check on the BACV, fine
did a crude pressure check of the inlet, ie blocked off the main air intake and blew down another hose! got a good feeling of pressure and no sounds of escaping air, but maybe that test is just worthless
how much of a leak does it take to stop low revs and idling?
I dunno!
I\'m finding it hard to determine what should be active during idle and what is dormant so that I can exclude it from consideration.
f\'rinstance, which jets supply gas at idle?
is the airflow meter involved at idle?
why is the Haynes manual;
a) only available for the US versions
b) useless at describing how things are suposed to work
ah well tomorrows another day
later peeps
its not looking good
presumably water in the oil doesnt help:(
or could this be another problem?
could the engine start and rev ok but not idle with water present in the oil?
yeah water in the oil isnt a good sign
i had the white stuff round the filler neck - but put that down to short runs and the time of year
are your getting white stuff on the dipstick ?
How much water is in the oil exactly??? Could be just condensation if the engine has been stood for a while.
With respect to your idling/running problem, did you remember to put the injector diffusers back in? as that can cause the car to stuter overfuel and then stall repeatedly.
Best of luck with sorting it,
Paul:)
thanks for the replies guys,
we\'re talking about lots of water in the oil:(
drained it last night, like chocolate milkshake
guess thats why the cooling system needed topping up!
so I\'m right back to square one, needing to take the sodding lump out again
just think how little time it will take you !!!
yeah! might be able to halve the time now!
only four months! :/
wonder what I\'ll f**k up this time?