Let's talk about fouled plugs

[JustJeff]

It seems that my front spark plugs are fouling. I've got about 800 miles on my rebuild. It's an almost stock S5 JDM 13B rebuild. It idled great on first start up and progressively the engine got more "pooty" and less smooth like you'd expect a rotary to be. I changed my oil at 500 miles and at that time changed the plugs. Front ones were dirty, even the threads on the plugs were notably darker than the rear plugs. After changing the plugs the engine purred beautifully again. But now 300 miles later it is again "pooty". I have not pulled the plugs yet to know for sure, but educated guess is they will be.

I know fouled plugs are common during break in, is it normal 800 miles into break in? One thing I did not do for my rebuild was have my injectors tested and cleaned. Any suggestions on who to send them to? Or any other advice regarding my plugs fouling?

[Gregory Casimir]

I'm currently having the same issue but i only have 8 miles on engine lol. I just got new plugs yesterday (thank god for warranty!) I know this sounds dumb but wouldn't a fuel pressure regulator kind of help prevent this?

[RICE RACING]

Fouled plugs are not at all common on a rebuild unless its a BDC motor LOL.

The plugs will only foul if your compression is fucked/low on your rebuild, check that and go see your "rebuilder" if its not up to normal specifications.

[JustJeff]

le sigh on the BDC stuff...if the BDC comments were an actor he/she/they would be typecast

I am my rebuilder I will ask myself in the mirror what I think......

[mattallac]

did you check if all the plugs are sparking ?

[RETed]

It's possible that the motor is still breaking in.
A compression test will confirm if this is the case.
From the evidence of the spark plugs, if the compression is indeed the culprit, you should get uneven numbers front versus rear.

Another question would be: how is your gas mileage?
Tracking your gas mileage while breaking in the engine can be used as a good indicator of the condition of the motor.

Have you checked the condition of the coils and spark plug wires?
Just as an easy test, try and swap the leads from front set to rear set and see if the conditions change?
Also, check the resistance of the spark plug wires - they should be pretty close to each other.


-Ted

[JustJeff]

Thanks Ted

I was going to wait to test compression until the engine had been broken in more, I'll do it this weekend. I had/have intended to track gas mileage, I keep forgetting when I'm at the pump. Spark plug wires are practically new, however I didn't purchase them new. A friend was parting his RX7 and had just bought new plug wires. I'll check all these things over the weekend.

[Garfinkles Motor Works]

I send injectors to RC Engineering ph 310 320 2277

[JustJeff]

I know of RC, the other one was Witch Hunter....I have someone local that can clean them, but I don't believe they do flow tests. Any other suggestions?

[JL1RX7]

You have any other ones to switch out?

[My5ABaby]

le sigh on the BDC stuff...if the BDC comments were an actor he/she/they would be typecast
:smilielol5:

[Pete_89T2]

I know of RC, the other one was Witch Hunter....I have someone local that can clean them, but I don't believe they do flow tests. Any other suggestions?

I've used Injector Rehab before, they do flow tests & document results for you:

http://injector-rehab.com/shop/

[RICE RACING]

Compression should NEVER EVER be low on a "rebuild" if it is then you have been ripped off with sub standard parts pure and simple.

Lots of people use dodgy rotor housings (grooves in them) or Apex seals that are as bent as Carson, it is totally unacceptable to have to "wait" for these parts to conform to grooves in a housing of for the soft as **** apex seals to wear flat lol.

Garbage in = garbage out

TEST YOUR MOTOR!!!
If the compression is low go see the low life who "rebuilt it" and ask WTF? this is what you should be doing first to eliminate the worst case scenario if you do not trust the job that was done.

All other checks like spark and fuel etc come after establishing that the motor is O.K. in the first place.

My 0.2 cents. :piggy: :ugh2:

[RICE RACING]

lack of compression = lack of heat *especially at idle and low speed running* and this is the root cause of spark plug fouling. It happens allot on old worn out motors................ should NEVER EVER happen on a new or rebuilt motor.

[JustJeff]

LOL Rice, as always you are borderline insulting and didn't even read my response to your previous advice about going to the rebuilder as I am the "low-life" who rebuilt it....

It's pretty clear you live in a perfect world where all cars and engines are built to appear in tuner mags and on the track. I unfortunately live in the real world where there was no rotary builder within several hours of me and no shop that wants to touch a rotary engine.

I appreciate your 0.2 (honestly I do), but I'd appreciate if you slowed down your ego long enough to read my responses. I do agree though if I had unlimited time, money, and the support of a local builder I would have loved to have put all new parts in. Unfortunately I had to make do with what I had...I hope you never have to face that humility :)

[RICE RACING]

That is why I am a Don Mega **** Bag :biggrinjester:

What seals did you use?
How was the rotor housing on the front?

As some sort of practical help, if you take it easy and they are factory apex seals it will take about 7000km of daily running to make them flat or conform to housing distortions.

I'd be interested in your compression test to see if this is the problem or not. ;)

FWIW I have "rebuilt engines for a total of $300 for mates many years back, one was a 3am job in his garage replacing a rotor housing with one I use to jack up my car! (filed the rough spots off where the chrome was chipped!) and slapped it back together with new Mazda Apex seals, that motor survived for years at 22psi boost on a T04 and about 480bhp lol, it was how I learned about the power of stock ports. Even on a dodgy rotor housing (by my standards 10 years ago) it still had good compression to not foul a plug, but ran OEm stock 2mm seals.

My world is not much different to anyone else's here, that is why I post up advice (and a bit of a rant some times haha)

[JustJeff]

I used Atkins apex seals, new side seals, new plugs for corner seals, FD springs, all new springs all around. I reused the oil control rings with new springs. I replaced damaged front housing and rotor with used housing and rotor. I checked tolerances with everything that went back into the engine and everything was within spec. It's a JDM engine and was very clean inside. The replacement housing was also JDM and the rotor is out of an FD.

I did a compression test the traditional compression tester way. Engine warmed up, EGI fuse out, CAS unplugged. I took the front leading plug out to test and the rear trailing plug out. I had trouble getting my compression tester hose in the trailing front because of a/c and p/s. I was able to get it in the leading hole and went with that.

Front has even bumps of just over 90 and when I let the compression build it was just over 100.

Rear has even bumps of just about 100 and built up to 120.

From what I've read you want front and rear no greater than 20psi so I'm borderline.

I ohm tested my plug wires
T1=5.47 and is less than 3ft long
L1=8.07 and is just over 4ft long

T2=5.11 and less than 3ft long
L2=8.28 and just over 4ft long

I haven't tested the coils yet, Final Four is on for one, but I also need to read up on how to test the coils.

[RICE RACING]

That sound acceptable to me using that type of tester assuming it winds over near 250rpm test std. Anything reading around 90psi on a normal gauge should not cause plug fouling.

Have a look if you have a leaky secondary fuel injector on the front rotor, you can check this by taking off the top half manifold and simply priming the fuel pump. This is/can be a common cause too.

[JustJeff]

Leaky injector was exactly what I was thinking. I'm occasionally smelling fuel but have no leaks. When I did the compression test on the front rotor I got an initial poof of gas smell and then it was gone.

I had been worried I had a coolant seal leak that could have been fouling the plugs, but I'm not loosing any coolant and I keep passing the bubble test...that and my plugs were dry when I pulled them today.

[JL1RX7]

Jeff I got two 460 injectors off another member and if you want them to use while you send the other ones off let me know.

[JustJeff]

I appreciate the offer, but I'll simply let the car sit and drive the van. I've got 550/800. I've got a RB exhaust, custom TID and Rtek 1.7 on the car. I even though the engine is in break in and not seeing any boost or RPMs above 4k...I'd hate to run the risk of running lean and detonating.

I have a question related to leaky injectors. I had engine parts powder coated and was not thinking about the dampener/regulator in the S5 secondary fuel rail. Should I be replacing my secondary rail because that dampener/regulator could have been damaged during baking?

[FerociousP]

I appreciate the offer, but I'll simply let the car sit and drive the van. I've got 550/800. I've got a RB exhaust, custom TID and Rtek 1.7 on the car. I even though the engine is in break in and not seeing any boost or RPMs above 4k...I'd hate to run the risk of running lean and detonating.

I have a question related to leaky injectors. I had engine parts powder coated and was not thinking about the dampener/regulator in the S5 secondary fuel rail. Should I be replacing my secondary rail because that dampener/regulator could have been damaged during baking?

The dampner is in the primary rail, the regulator is in the secondary rail. I'd tee is a fuel gauge before replacing the regulator. test are pretty straight forward... but, both the front and rear would be flooding if your pressure was too high.

[JustJeff]

The dampner is in the primary rail, the regulator is in the secondary rail. I'd tee is a fuel gauge before replacing the regulator. test are pretty straight forward... but, both the front and rear would be flooding if your pressure was too high.

That's what I was thinking. The fuel rail is open so both would flood.

[Pete_89T2]

If you have flooding in only one rotor, it could be that one or both of the injectors on the flooding rotor are leaking down. In other words, the injector is gummed up and not closing fully when you shut the car down, so only that rotor floods.

[JustJeff]

I've been driving the car daily. Fuel injectors were sent to witchunter for cleaning. I still have fouling plugs. So far it has only been the front rotor that is fouling....and I bet when I pull the plugs I'll find the same thing.

[WankelsRevenge]

I havent read this whole thing, but are you still running your OMP? If so could it be an issue with them spraying too much oil into the chamber? Also maybe youre not getting enough spark in that chamber which could be causing you to not get a complete fuel burn. Granted, Im just pulling these ideas out of my head, so Im not sure how plausible they may be.