93, bnr, pfc, exhaust, meth

2k miles on new engine and i took the car to the builder to fix the idle. He tells me it has low compression because it wasnt broken in properly.

The cars idle jumps up and down and it feels like its on one rotor for a second when you hit the gas in nuetral, very boggy. He said it was the powerfc so he change the idle to manual and now it's worse.

I never got the above 4k rpm or above atmospheric until 1300 miles. I changed the oil at 500 and 2000 miles and the plugs at 1000.

He didn't give me compression numbers because he just checked the idle.

The car pulls great at 8psi. I can't find anything on "bad break ins" except for blown engines. Could it really be?

 

You know, I have a similar issue but no tune yet, just base map. My set up is almost the same too. I'll let you know after my tune this week. I have your set up w/o meth and my rebuild has 1 piece ceramic seals.

 

Get a second opinion.

 

Sounds fishy to me. How can you know it has bad compression without testing? Who is the engine builder?

 

You can perform a compression test yourself its really pretty simple. Just search for how to do it or I believe there are details on rotaryressurections website.

 

No way Jose. Who is the builder? Absolutely get a second opinion.

 

Bad break in my ***. Rotarys dont need a lot of breakin to be reliable. Just a few hundred miles to seat the seals. We need more details on the rebuild as in what was actually replaced?

 

im getting around 120 on rear 110 on the front.

The engine was overheated until it locked down. An oil shop didnt put oil back in my car... yeah.
Everything on the block was replaced except for the rotors. The power fc and bnr twins were installed during the rebuild.

A very reputable company built it (though the rotary shop i'm working with sent it to them) and after seeing the compression I'de say the engine is fine and it pulls pretty damn well.

 

Sounds like another issue. Those are solid numbers.

And yeah, lesson learned. As you now know....NEVER take your FD to an "oil shop".

Do you have a wideband?
Check your plugs?

 

Changed the plugs with the test. i need to get it tuned but I'm assuming that it should run fine on stock pfc map.

 

edit: nvm.

 

Are your running other than factory size injectors?

Are you using the stock MAP sensor?

 

stock injectors and map sensor

 

What was the condition of your wiring harness? Also did you pay to have your injectors cleaned and flow tested? If not, your asking for trouble not knowing their condition. No rebuild should ever be done without checking the injectors. Especially when there 20yrs old.

 

I know nothing about the wiring harness or the injectors. I plan on getting them cleaned and the secondaries enlarged soon.

 

If you are dealing with the original harness, and it looks crispy, I recommend a new OEM.

If the car is untuned, try doing a map re-initialization with the Commander.

A few preliminary things to look over.

1. Double check those plugs. I've seen brand new plugs have issues.

2. To ensure each wire is getting spark, put a timing light on each wire.

3. Ensure your TPS is adjusted properly. You can check the voltage in the sensor section of the Commander. Ensure the car is warmed up if you still have the thermowax, as it will press the throttle open if not warmed up completely and give you a false reading. FSM shows desired voltages

 

OP was asked last time his car was here if he had gotten into boost in his 1000 miles recommended break in period for his new motor.

The car was first started up with a decent 18inchs of vacuum being pulled at idle even after the initial first drive from us.

No compression test was done by us because no clear signs of anything wrong except for the now low vacuum at idle compared to first being installed.

Car does drive great and pulls hard. It had the Apexi pfc bounce at idle when we got it and he just wanted us to make it go away. So we set it up to run manually with no idle air control so he could mess with it later on.

Car didn't have an issue with idle when we drove the test miles, But it now sounds like a vacuum leak to me.

Also the bogging down is probably due to the throttle body adjustments being off.

And there is no question about the car being reliable at this point clearly with the compression numbers, also has good hot and cold start last time the car was here.

And the wiring harness was brand new at original build. It was a brand new Mazda with around 4-5k miles on it.

Maybe poor vacuum on gauge has something to do with the bouncing idle with a vacuum leak.

 

I was under the impression that changing the idle to manual was to fix the problem.

I know for a fact that i never got into boost or above 4k rpm in during the break in. But apparently the problem occurred during the break in.

The engine at low rpms feels the same as it did during the break in as far as being very laggy and boggy thus making it difficult to start from a stop.

I just noticed the idle vacuum it's at 15psi. i think i remember it at 18psi as well maybe it has something do with the sequentials system glitch and the swap?
But the car technically had the same problem with good vacuum.

So I just need to get the throttle body adjusted during the tune.? I'm afraid (paranoid) that It's a deeper problem that i need to fix before the tune.

As long I have good compression numbers I'm not worried. This idle is obnoxious though.

Wait so it's not the pfc bounce if it bounces on manual right?

 

A wide band would really help you diagnose what is going on with the "bogging". It will definitely aid in the idle as well. If the idle is lean, it can hunt as the ECU tries to keep it alive. Rich can cause the bogging.

When you started with the PFC base map, did you initiate the idle learn?

Definitely good news on the harness.