Yeah, I'm running goopy seals, even if my engine were tuned to the max it should be able to produce enough power to phase them. 15 psi...hahaha the engine has never been higher than 5psi. I removed my boost controller while the engine was being built and the Watergate is thoroughly ported. At wot it will typically hit 4-5psi fire a second and immediately start to bleed off.

I don't work in a garage, and this is my daily, so diagnostic rear downs are not on the to-do list. Any other suggestions are greatly appreciated

I was thinking perhaps it has something to do with the TB because it rubs perfect before the thermowax heats up.

Our perhaps the alt, since voltage drops sharply, but that's a chicken and egg situation.

 

update?

 

Well, I started a new job and my commute is only 1 mile so I haven't had much time to mess with it. I bumped idle to 900 and it idles nice and smooth. Gas mileage is substandard, but that is not unexpected.

I'm thinking its a timing issue, and perhaps the fact that I'm running 4x 9x spark plugs is contributing to the poor mpg as well.

The next step is to get a timing light and make sure that timing is on as well as install some platinum plugs of the appropriate heat range.

 

sounds like one of the seals warped due to sustained inaudible detonation, possibly due to timing. keep in mind the FC pulleys can be off time if it was ever mixed up with another hub/pulley combo.

either that or an imbalance allowed a rotor tip to graze the housing and pinch the seal which is having difficulty springing out.

i actually see rotor tips scuffed quite often which is usually due to an over-rev situation, hard fuel cut or misfiring at high RPMs(my second guess as to your problem, possibly due to the hot 7 plugs that were in that housing along with the boost leak creating an overly rich condition and blowing out the spark).

Goopy seals can handle a bit of abuse but they can only tolerate it in short bursts, even at sub 300whp figures any seal can still give up if the conditions are surpassed. the good news is it is still drivable, some other seals would have left you running solely on 1 rotor in the above situations.

 

Thanks for that highly informative response. I know who's building my next engine...

I doubt the pulleys were miss matched because the entire rotating assembly(pulleys included) came from an original s4 n/a engine. However, when I came to pick up the car originally it wouldn't start unless the alternator was unplugged and when I returned the next day he informed me that the reason it wouldn't start was because the "timing was off"

Rotors were NOT cleaned prior to assembly, so I wouldn't rule out an imbalance (s4 car rotors aren't particularly consistent in that respect to begin with). However it only saw 7k at the top of 2nd and started sputtering well before red line in 3rd.

As far as spark goes, would you consider 7's too hot even under 5psi ? After switching to 9's all around it seems less responsive. Slower to start and I'm pretty sure fuel economy has worsened. Not saying the plugs are why, but that's been my observation so far.

Yes, hooray for goopy seals, not only is it drivable. But pulls good vacuum and idles just fine. That's what makes this diagnosis so difficult.

 

7's are fine until they hit rich mixtures, then they misfire earlier. normally i run all 9's between modified stock turbo engines up to mild single turbo upgrades, at about 350whp you normally have to upgrade again to even colder plugs.

in this case it sounds like a single seal warped, as an apex seal warps it runs hotter than the rest because it cannot cool against the rotor housing but you may see some warpage on the other 2 due to the excessive EGTs from that rotor. i wouldn't push it too much until you can get a chance to break it apart, be sure to premix more heavily since if the seal is warped it will be running less than half the seal friction surface. depending on the extent it may break itself back in if given enough time.

 

What would running too rich on the stock temp plugs do, just cause them to foul faster? I see you say they misfire earlier as well.

I'll be running a stock turbo with full exhaust, 550/720s, walbro 255lph, and rtek 1.7. Stock intake, tmic, and fpr.

Rotary > Pistons

 

with the NGK plugs the lower number is a hotter plug, higher is colder. 9's are a colder plug than the 7's. 7's self clean better but misfire at lower EGTs/power levels, so they foul less than 9's.

ignition breakup doesn't necessarily cause damage but the side effects it causes may, but normally you can feel breakup before it can be to the point of damaging. it's difficult to tell if there was a lean spike or timing issue without any logs.

 

Good to know.

I guess I need to check timing and do another compression test to see if it's even worth investing any more time or money into this engine.

 

Update!

Picked up a craftsman timing light off craigslist and checked the base timing...wow. WAYYY off, as in the timing marks didn't even show up. The marks were almost non-existent so I had to re-file them and add a little paint.

The first time I mis-labled the leading vs trailing marks and re-stabbed the CAS , sad thing was it still ran better with the trailing mark set to TDC I drove it home and it reved up quick but had no power and only pulled like 10" vac.

I realized my mistake about halfway home but was too tired to mess with it, so the next day I labled the marks properly and re-stabbed the CAS, timing is now spot on. It runs a full point leaner at idle, accelerates more easily and runs much smoother overall. only issue is that it now pulls around 14" vac wereas before (with the nonexistent timing" it was around 18".

I think the moral of this story is don't trust people who work on carbs near your fuel injected car ....even if they build 10 second (carb'd) race cars.


Karack: As far as the seal wearing back in, what would you think the odds are?

 

Glad to hear that things are headed in the right direction with your car

 

While it's good you found the cause...changing the timing won't fix those seals. It's been like 6 months. Pull that engine already and pop off the back plate!

 

Sounds good and all, but when I pull the engine it's getting a full rebuild. It was a budget rebuild that put me in this situation in the first place, so I will continue collecting parts and and preparing to build a proper 400 whp engine.

For now it runs just fine and whatever damage has been done is done, so it'll be fine.

I have enough spare parts to put together an n/a engine (which will ultimately find it's way into a track car) so I might build that and toss it in to speed up the timeline on the tear down, but I would prefer to use turbo irons which I still need to acquire.

 

Every rebuild is a budget rebuild. You need a newer more reliable car for a daily.

 

Lol, that would be a budgetary setback. If someone gave me a beater that's fine, but I'm not going to waste money on one when this car has been reliable (timing issue aside). I hadn't opened the hood in months prior to this except to change the oil. Now it runs even better so fuel economy should be back to 17/20+ and considering my 1 mile daily commute that'll be just fine my new engine comes together.

That being said, I do have another fc (the aforementioned "track project") which doesn't currently run. It will get an n/a engine, manual rack etc and be a very simple/reliable car to cut my teeth on at the track. I could daily that for a while once the engine is built. Or I could put that engine into my currently daily and tear down the one thats in there now.....not sure whats more cost effective just yet.

 

the seal should wear back in but it depends how badly warped it is, if it is cracked or if it is something else like a broken/stuck corner seal. if it is a warped apex it could wear back in but would take many thousands of miles.

the only way to know when it has is by doing periodic compression tests and not driving it hard until compression has almost normalized. is all this worth it? not really, but you should probably be able to limp the car around until you can tear it apart.

 

Sage advice I'm sure, and thats what I shall do. Just keep driving and not worry about it. Not going to up the boost or stress it, and it should live a reasonably happy life @ <5psi.

In the mean time I'll be on the lookout for some turbo irons to complete the N/A build. Only question is SP or BP?

 

I stabbed mine hella wrong too. When I stabbed my CAS the front pulleys were off the engine, so I thought I was supposed to stab based on hte big dot marked on the from hub. Didn't realize my mistake until I hit it with the light and saw the two marks on the Pulleys, and it was almost 180 degrees off.

 

What kills me, is that stabing the trailing as the leading still produced better results than the way I picked it up from the shop