Issue came up on Dyno and I am baffled
 

Bear with me on this one I am going to give as much info as possible, hopefully someone else has had this issue as well and can help me out here.


We broke in a new 13B-REW engine on the street it has about 600 miles and another 3-4 hours of low RPM break in.

I run a Motec M4 with full Lambda and datalogging so we did some rough street tuning making sure it was not running too lean and it was not so we were happy breaking it in, taking it on road trips and just running it, never an issue. I even did some hard 3rd and 4th gear pulls on the street as we got ready to dyno it and it ran strong and again, issue free.

So we take it to the dyno. The shop had these evacuation pipes that hook up to you exhaust and run through some huge mufflers then outside.

We do a short 3rd gear pull to make sure everything is well and it is. Then we do another 3rd gear pull to 8,500 RPM, all is good. Except we see the small T04E is just not making power over 8K RPM so we decide to do a 4th gear pull to 7500 RPM at 1 Bar, and see what we got.

As I approach 7,000 RPM the evacuation pipe pops off and I blast black sooty exhaust all over the rear wall of the shop. Then as I let out of it it stalls, it will not restart at all.

Its not blown, the compression is great, its getting spark, its getting fuel. We let it sit overnight and it starts but is not happy.

Details about the car:

13B REW, Agressive Streetport with a HKS T04E Turbo.
Throttle body 30% bigger than stock custom butterflies and port job.
Intake tract ported 30% over stock and match ported
Stock primary injectors 1300cc secondaries
Custom fuel system, -8 from tank to fuel rails
Tornado fuel pump, custom pickup in tank - fuel system will support 700RWHP.

Stock FC Coil packs that have been modified to create more spark.
Stock spark plugs

Thats everything I can think of that is relevant.

Cliff notes:

-Car runs great with new engine
- break in s problem free with lots of powerful pulls in 3rd and 4th
- Go to dyno car stalls from backpressure and will not restart until next morning
- Suspect backpressure kabookied out Motec?

Dunno, but nice to see you are still around. Did you fix the diff clunk yet?

John

What do you consider good compression and more important what did you use to check it with?
Check your spark plugs.

How have the coils been "modified". Have you verified they are still working correctly?

+1
Try changing out for a new set to see if this helps.


-Ted

I am not still around, Scott made sure of that. I would have posted this on his forum but he has me locked out in the Que.

New Mazdaspeed Comp mount and then JR made a custom brace, I broke my last diff mount.

We changed the spark plugs on the dyno when it would not start to 4 fresh ones.

The coil packs had been in the car at least a week leading up to the dyno day.I drove hard on them and they worked great, they also eliminated a mid RPM 1/4 throttle stumble I had been dealing with.

Everything worked fine leading up to the dyno, I am positive the back pressure did something.

The car ran very strong all month leading up to the dyno day.

We will put another new set of plugs in and see if that does it.

Compression checked today.

95PSI on all 3 faces front and rear. Mazda Compression checker used. Engine has a total of 6 hours on it since first startup. I expect the compression to rise a bit once it totally seats in. At least a blown engine is ruled out.


Put a squirt of Protek-R in both rotors and started it up and it ran great. Like nothing happened.

So this leads me to wonder if I am not tuned for enough fuel on startup.

Gonna check out my maps.

BTW - My oil injectors are removed I rely totally on premix for rotor housing lubrication.

I guess I just freaked the car out with all the back pressure on the dyno.


Has anyone else ever had this happen?

check for vaccum leak, if it was the first few times you were bringing it to a full bar, probably knocked off a vaccum source somewhere or its leaking a bit mouch.

check MAP sensor and its line.

then check all vaccum/boost lines .

If it starts and the rpm raises or drops probably that.

I had something similar happen a year or so ago after I put the stock exhuast on a friends for about two days while waiting for the RB exhaust he had to get back (had taken it to a shop to get O2 sensor bung put on). The engine totally exploded the muffler when we were decellerating through a turn, stumbled, and died... We checked compression and it was good but we couldn't get it to start... We ended up push starting it with another car and pillows in between bumpers... lol... it worked though but it puffed a bunch of gas smelling smokie gook out the back... I always figured when the muffler exploded it must have not had enough back pressure to run right or somethign and flooded or something cause it was smokie like due to running rich for about 3 minutes... Everythign wokred out though and it never had a problem (that I know of) related to the exploding muffler... On a side note the cop thought we were fucking with him at first when we pointed to the debris (two metal end pieces and part of the side wall) on the side of the road and told him it was the muffler... pm me if you have any more questions about the incident...

O.K. - We added some fuel to the the car at startup and it starts up fine now. I have stock primary and 1300 secondary.

We changed to fuel from 25% at startup to 50% and now it starts up fine and happy.

Too little fuel at startup or are the injectors shot?

Keep in mind I roasted this engine before this rebuild, I ran it at 280° for long durations on a road course, and the aerators on the injectors were melted. I never though that maybe my primaries are shot.

I am ordering some new primaries and maybe some 1600cc secondaries along with a GT35R so I can finally get the power I have been searching for out of her.

although the 35R is a GREAT turbo. id go along with the T04Z. i just here sp many ppl complaining about it running out of breath and are dissappointed. just my $.02

if everythign else checks fine, maybe you can check your turbo oil seals as a last resort. Do you have an oil resrictor?

Have you checked the timing? Seems like you have split timing. Does it idle bad than before. Does the rpm stumble around 3k??