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]

Originally Posted by JustJeff

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

[Pete_89T2]

Originally Posted by 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?

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.

[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