Black13B

iTrader: (1)

so i was browsing around and couldnt find the same symptoms as me

car has been sitting without running for just about a year.. and it runs alright when you get her started up.. but under "load" or.. a little stress.. sounds alot like a piston engine with a spark plug gone..

im new to the rotary scene (yeah i know about the L and T plugs for each rotor) but im sure you guys know what i mean about a piston engine with a bad plug..

wanst sure if theres a way to tell exactly whats up using that type of analogy..

anyways its rough getting up to speed.. and she doesnt like to GO in 1st or reverse.. doesnt like having to make itself move..

also it idles REALLY rough and usually stalls after driving.. it takes a bit of attention and patience with the gas to get the revs down to idle after starting it (if you CAN start it.. i need a new battery - luckily the cavalier is always happy to lend a boost) but like i say after coming out of gear the revs drop to idle.. then it gets little choppy and decides to stall out..

previous owner ("charger-" over on this board) did the MMO treatment a few months ago, but it still hasnt seen the highway for a long drive

he said its got good plugs in it now, but one sitll might have gone bad.. or something..

what do you guys think? my main idea was (tomorrow) to go get new plugs for it, and take it on the highway.. maybe throw something in the tank (ie - injector cleaner or something - another thought was condensation getting into the tank after all that time, then having not-so-waterless fuel or something

anyways any responses would be very helpful.. boosting the battery and keeping your foot on the gas when its out of gear isnt the easiest thing to do all the time..

thanks!

Black13B

iTrader: (1)

https://www.rx7club.com/forum/showth...hreadid=177569

ive been keeping an eye on this thread too.. keeping things in mind as well..

J-Rat

iTrader: (2)

Ummm... I would always go with a compression check.

Jarrett

Black13B

iTrader: (1)

how do i do that on a rotary though?

(lol.. sorry about my newbness)

Black13B

iTrader: (1)

btw i should also mention that when you do get to softly drop it to idle, it will usually (depending on what it was just doing) idle just fine.. just takes alot of patience to get it there..

idles between like.. umm 700ish to 800? idles just fine when you can pull it off

J-Rat

iTrader: (2)

Alot of blown motors will still idle....I have one in the back that will. You can compression check with a regular compression tester, you just have to hold the pressure release button down in order to see 3 distinct bumps of compression.

Jarrett

Black13B

iTrader: (1)

ahh ok.. sounds good too me man.. ill try it out when i get it up to my shop.. thanks!

any other suggestions? thinks to look for, or some specific symptoms of.. anything?

marcus219

Just pull the two top plugs...pull the CAS wire, on the drivers side of engine, front cover of motor, looks like a mini distributor kind of, black cap..white connector. Good luck.

Barwick

Sounds like an ignition problem to me. I had that problem on my Civic when Raptor13x accidentally went from 5th to 2nd at 75mph, revved to about 9500 RPM. Engine went UP, body/hood went DOWN, spark plug wires that ran across top of engine got pinched, the #1 cylinder one got cut and worked ok unless it was heated up and under load. It would short to the block or some other part of the car, causing the cylinder to not fire when under load.

Might want to check all the stuff dealing with ignition, plug wires first, plugs, etc..

Black13B

iTrader: (1)

whats the CAS wire's function?

and i was thinking if it is misfiring or something, theres no relation to the trailing plugs, right? it STRICTLY just burns up unused fuel.. doesnt it? or does it play more of a role than just emissions?

hypntyz7

First order of business, compression test. Then, and only then, troubleshoot the control systems.

Here is a page I have written for my webpage but have yet to post it there.

Rotary Engine Compression Check

Often people chase after problems with their RX-7 for many hours, even weeks at a time. My first rule of troubleshooting a rotary engine is to first perform a compression check. IF this reveals no problems with the short block/internals, then a control system or condition is at fault. I have looked at, worked on, or purchased many 7’s which had blown engines, all the while the pervious owner thought there was a fuel pump, fuel filter, sparkplug, coil, computer, etc. problem causing the car not to run properly. Here are steps to performing a compression check with or without a tester.

Poor Man’s Compression test(free):

1. remove lower sparkplug and wire from front rotor.
2. remove EGI fuse from underhood fusebox to prevent fuel and spark while testing.
3. have an assistant crank the car over for you, while you listen under the hood at the compression pulses coming from this plug hole. IT is recommended to put your hand/finger right in front of the hole to feel the pulses of air.
4. There should be one strong pulse/whoosh of air per full rotation of the crank pulley. Use the timing marks on it as a reference. There should be 3 even pulses in succession, without skips or gallops.
5. IF one or more pulses are weaker or non existant, this indicates (usually) at least one blown apex seal and severe internal damage. A full rebuild will be required, and no further troubleshooting will help.
6. IF this chamber passes the compression test, replace this plug and repeat for the rear. The rear rotor blows more often then the front on 88 and prior engines, and the front rotor blows more often on 89 and later engines, for reasons unknown.
7. With both lower plugs out at one time, you can listen/feel for compression on both rotors at once. This should be a rhythmic ch-ch-ch-ch-ch-ch sound, like an old steam engine train, alternating front to back, once per rotor per rotation. Any skips or galloping indicate loss of compression.
8. note that this procedure can be used to test junkyard engines or engines out of the car. You will need a 19mm socket and ratchet to turn the front crank pulley bolt clockwise in quick, long strokes as possible to get a somewhat accurate reading. You will obviously not be able to turn the engine much at a time, so try to count each pulse as you go.


Compression test using a piston engine tester:

1. note battery strength. A weak battery will yield low compression results.
2. Remove both lower plugs and wires.
3. remove EGI fuse from engine fusebox.
4. have a friend floor the accelerator pedal, opening the throttle for more airflow
5. insert your tester into the leading hole
6. hold the valve on the side of the tester open
7. have your friend crank the car over for 5+ seconds.
8. observe the needle bounces. You should see 3 in succession without skips, even bounces, in roughly the 30-35psi range.
9. let out on the valve now, and let the tester reach an overall compression value for all 3 faces(highest of 3 will be displayed). 115+ is like new, 100-115 is healthy, 90-100 is getting weak(1 year or less in most cases) below 90 could blow at any moment.
10. repeat for opposite rotor. Note difference in overall compression between rotors, which should be no more than 20psi max.

FCdemon

is the gas a year old--> if so, drain it and refill with fresh gas!! have you changed the oil, coolant, and plugs, and all filters? that'd probably be a good place to start.

DrifterFD3S

my car does the exact same thing... its a 88 GXL and it WILL NOT IDLE for **** unless you coaxe it into it for like a full minute of playing with the revs, and even then, it jumps from 1000-1500 (very annoying) and floods almost every time i turn the car off (warm or not) and worst of all, ITS SLOOOOWWWW my friend beat it real bad in a foot race. guess ill try the po' mans compression test tommorow
cuz thats what i am!

Black13B

iTrader: (1)

hoh! poor mans compression test owns.. i think im gonna try that.. i know its not the most accurate way but its the quickest way to diagnose the situation..

thanks dude!

i think the internals are ok though.. cause when im out on the road.. it still has power... i got up to 110kmph in 3rd, and it still woulda picked up more speed, it just sounds like its missing a little bit.. almost like the fuel (or spark) is a little fouled up somehow.. i can idle it up high with a light foot on the gas and she purrs really nice.. HUMMMMMMMMMMMMMMMM same with letting off the gas while in gear at like 3k rpm.. she hums real smooth.. but seems like anything past 1/2 gas pedal travel she starts to get rough..

but the compression check wouldnt hurt - so im gonna try it

i just filled the tank right up (it was on empty and ran like poo, then i put in a 1/4, and it still ran kinda ghey, then i filled it right up but i parked it so i havent taken it out and about on a full tank)

Fingers

Chances are likely that the MMO treatment clogged up the plugs. It happens all the time.

Change yer plugs, and it should get better. If not, do a compression check. In fact, do the compression check while changing plugs makes life easier.

Barwick

I still think it's got to do with something in the ignition, my Civic did the same thing under load (ONLY under load once it was warm.. not at idle, not while decelerating, etc.. but only when under "heavy" load (like half throttle in 4th gear cruising around))

Black13B

iTrader: (1)

could be barwick but we will have to see

i just topped up the coolant, checked the oil - so those are ok

i couldnt find the CAS at all though.. i dont have the eyes for it yet..

anyways

i pulled out the lead plugs - they are a little um.. black and oily.. so thats likely a problem..

compression check (ghetto style - but REALLY easy and handy) yielded excellent results - the thing has awesome compression - really smooth, consistent, and rhythmatic

so im off to crappy tire to get some NGK plugs if they have them, and ill be back to let you know the results

charger-

iTrader: (1)

Hey guys, the car was mine. I parked it last March after the clutch went. I put it on jack stands and pulled it apart in about a month (in spare time). When I realized it wasn't going to be out of the garage soon i put some MMO in it and manualy turned it over (used the belts). This was probably 2-3 months after it had last been run. I tried starting it early winter after the cluth swap was finished, but couldn't start it. Mind you it would have been well below 0C and I'm pretty sure the cold start system doesn't work.

Anywho with crappy plugs in it last week it wouldn't start. I swapped to some better plugs but ended up flooding it (Its been awhile since I've been through the fuse routine!) I added more MMO to get the compression back, and it look like the plugs are all fouled now.

Anywho that will be part of the problem. Is it possible the coils could have gone bad from just sitting? Just putting this out there so you guys can better help Colin trouble shoot the problem.

Black13B

iTrader: (1)

lol thanks dave

another quick one - specific torque settings for spark plugs on rotaries?

Black13B

iTrader: (1)

n/m.. 9 - 13 ft/lbs i found out..

Black13B

iTrader: (1)

soo.. trailling coil got hot.. replaced it with another one.. seems better but still seems could use new plugs.. runs smoother, "misfires" less, but still DOES misfire.. comments, or ideas anyone?

DrifterFD3S

if its just off idle when misfireing, its kinda normal, ive heard of A LOT of rx7s having that problem. very backfiry and ghetto sounding when just off idle happens to my car too.. odd how we have the same ailments

Black13B

iTrader: (1)

definately.. ive seen quite a few members complaining of the same problem

still, my coal black NGK BUR7EQ's could use replacing.. but the new coil seemed to help alot.. now it actually smokes regular out the exhaust.. (before it wasnt, unless you punched it and it was all blue)

the idle (when it drops down from 1k+ at cold) stays usually between 800-700, but sometimes it gets in a pattern of 600-800.. which.. doesnt sound nice at all.. when it gets to 600 she almost wants to give out.. but doesnt.. just picks up to 800, then drops back down.. doesnt seem to bad when i explain it here, but when you listen its like "woah she gonna stall!!!... no wait.. OPP HERE IT COMES... no.. OHHH!!! oh, no, not yet.. oooOOOHHH!!! nope..."

Aaron Cake

iTrader: (1)

You really need to do a complete tuneup (all fluids, belts, plugs, wires, filters, timing, TPS) as well as a complete flush of the fuel system. Probably also need a professional injector cleaning. Also, vacuum leaks, vacuum leaks, vacuum leaks.

Doesn't sound like a compression problem.

Black13B

iTrader: (1)

like i said earlier the ghetto style compression "test" seemed very steady and popped out the air nicely

oil is fresh - coolant is good - umm.. belts are older - plugs are fouled and im getting new ones tomorrow - plug wires (i hope thats what you mean - the plug wires) are new NGKs - fuel filter i am unsure of when it was last changed - i dont know how to check or change the timing yet, and i have not investigated the TPS yet at all (unsure of that too - need to read up) - there could have been condensation in the tank.. but i filled it up and just threw in a lil bottle of injector cleaner..

i would like to get the new plugs in and burn off the whole tank and take it from there.. see how it goes..

the newer trailing coil seems to have helped decently though..