mkd

iTrader: (8)

I'm kind of at a loss diagnosing an issue I've been having for some time now. I'll try to keep it short.

About six week back I noticed that my car was idling slightly rough. At that time, I was just off on a 200-mile drive to visit my folks and do some wrenching. On the drive there, I noticed that throttle response seemed to be a little sluggish, but can't comment on power as I wasn't really doing any power pulls on this journey because the car wasn't boosting properly. I got to my parents place, fixed the boost issue, (swapped Charge Control and Turbo Control solenoid connectors), and fired the car back up for the drive back home -- it was once again idling rough, now noticeably worse, and there seemed to be more blue smoke on startup than usual. After hitting the road the car really seemed to be lacking power, especially on the low end. About 50 miles or so into the drive the car seemed to be loosing power, and after a few pulls it abruptly began to run much worse. Over about 4-5k it revved relatively smoothly, but lacking full power, and letting the RPMs drop down into the 1-2k range it was very hesitant to rev back up. At one point I pulled off the highway and let it idle, and it sounded almost like a helicopter -- deep and rough, loping, sounded like it was running on one rotor or something (see video below, taken this evening). I was afraid if I turned it off it would not start again. So I limped the car home -- hard to tell if it continued to get worse at this point, but I was afraid it wasn't going to make it the remaining 100-150 miles back.

Some details that might be relevant:

• IGN-1A
• Stock primary injectors, Bosch 2200 secondaries with RP rail
• PFC
• Motor and car have about 38k miles

Over the past several weeks I have been doing a lot of diagnosing.

• The T1 plug was not torqued in and was loose.
• Pulling the T1 plug wire while the car is idling doesn't seem to do much, if anything.
• Pulling both L1 and T1 wires make it idle worse, but not hugely.
• I did pull the rotor 2 plugs but at this time I can't recall what affect that had (I will have to test that again)
• L1 & T1 plugs were very badly fouled -- no visible white spark markings (see image below)
• L2 & T2 plugs looked rich but had white spark markings (see image below)
• I checked the igniter connector for power or shorts and it seemed fine.
• I checked the Leading + T1 & T2 ignition signals with an oscilloscope and they looked fine.
• I tested the plug wires and they were all fine.
• I checked my SBG IGN-1A harness and it seemed fine.
• I made my own IGN-1A harness (this was a bucket list item anyway, as the SBG seems to have a rather weak ground with a single 12ga wire shared for both housings) -- nothing changed with the new harness (see images below! I'm going to do a write-up on that as soon as I get the car running...)
• I checked each coil for spark in open air and only two or three of them sparked (I know this is a big hint here -- unfortunately my notes and memory are crap so I will need to check this again)
• I bench tested the coils (not sure the proper way to do this -- couldn't find any info online) -- two of them had about 20K Ohms between the charge pins (D & E), and two of them had about 1 Ohm. I bought four new coils, and all four of the new ones had 20K Ohms across the same pins (two bad coils?). I open-air spark tested all the new coils and they all worked. I installed the new coils and nothing changed (I'm going to pull them out and open-air test them again)
• I pulled the PFC out and opened it up and can't see any burned components or traces.
• I checked the GM 3-bar map sensor and it seemed to be reading correctly. I also swapped it for the OEM map + OEM ECU and nothing changed.
• Fuel pressure with ignition power on/motor off is fine.
• Fuel pressure at idle is fine.
• AFR seems a little rich at idle? (~11.4)
• TPS voltage is ~.65 at cold idle.
• Fuel temp and water temp both look fine at idle (sensors are connected and good)
• At some point I pulled a housing 1 plug and a housing 2 plug -- one of them was covered in gas (rotor 1?) and the other smelled like gas but was not covered (sorry my notes on this are crappy -- not sure which was which). I left them off overnight, and then tried starting again in the morning and nothing changed. I should check them again after a minute or so of idling.
• Recently coolant seems to be disappearing and several times the temp gauge has started creeping past center shortly after starting a drive -- I have to pull over and top the coolant off.
• I checked for oil in the coolant and didn't see any.
• A couple months back compression on rotor 1 was about 95/95/95. Rotor 2 was about 110/110/110. Testing compression cold today on rotor 1 was about 75/75/75 (?). I will try again warm + try adding some oil in a plug hole.
• There always seems to be a lot more smoke at startup than there used to be (looks blue and smells like oil).

One thing I found extremely suspicious is that a few days ago, the ignition power was on, and I heard a humming from the engine bay. I few moments later I heard what sounded like a worm gear stripping (see video below) -- a little hunting and I discovered it was the AWS solenoid. That is very strange considering I disconnected the AWS wire at the ECU connector since I'm using a PFC, so it shouldn't even be connected! (engine harness bad?)

Some ideas on what to try next:

• Open-air test the new coils again
• Check for gas on the plugs
• Check the crank angle sensor signals. The leading sensor is brand new with under 1000 miles on it.
• Pressure test the intake to identify any large leaks
• Check rotor 1 compression warm / after squirting some oil in a plug hole
• Check the PFC logs from the drive home to see if AFR looks normal (stuck open/closed/clogged injector? bad injector harness wiring?)

Idle:
Light throttle needs to be applied to keep it from stalling. If I wedge a flat-head screwdriver into the throttle body butterfly it will idle on its own.

Plugs:

(Left to right: T2, L2, T1, L1)

AWS noise:

IGN-1A harness:


Any suggestions greatly appreciated...

FührerTüner

iTrader: (5)

All that troubleshooting and not a compression test? Seems like you lost rotor 1 to me.

DaveW

This^

DaleClark

iTrader: (55)

Compression test both rotors. From the video it sounds like a blown engine - I know that sound unfortunately. Don't do any further work until you know for 100% the motor is strong and solid. If possible use a rotary compression tester. But I have a feeling you may have bad news.

That is the ISC making that sound, not the AWS. The ISC will make noise some times with key on/engine off. Nothing too big there.

What plugs are you running? Any reason you are running exotic plugs?

Dale

mkd

iTrader: (8)

See, this is what happens when your post is too long, nobody reads the whole thing!

I do, in fact, have a rotary tester. Will re-test today or tomorrow. This one is from yesterday.



It’s not in the video, but I put my hand on the AWS (the solenoid at the back of the UIM, with the hose that goes to the large nipple on the intake elbow), it was physically vibrating, and upon unplugging the electrical connector the vibration and noise immediately stopped.

Plugs are NGK 10.5 as I’m running BNR stage 2’s.

DaleClark

iTrader: (55)

The picture you posted is the raw test, what are the numbers when it's corrected to 250 rpm?

70's is pretty low and the numbers will scale lower with the 250 rpm correction.

I saw that you had tested but you only had the numbers on the front rotor. That's half a compression test .

Dale

mkd

iTrader: (8)

Crap, you’re right!

Fair enough, lol. I guess I was working on the assumption that since pulling the plug wires off the front rotor had little effect, that would be the problem area. I’ll warm it up and test both.

I guess it’s speculative at this point, but I find it odd that compression would fall evenly on all rotor faces, and do it in the relatively gradual fashion I describe. If an oil injector were clogged, for example, would that explain a failure in this manner? Or if there was something wrong with the OMP, would my only clue be crappy compression all-round?

j9fd3s

iTrader: (3)

compression will also change with how the car is running, so warm it up, and hopefully get it to run nicely, and then compression test. if the numbers are even, but low its worth going to the next step, which is to start swapping coils/injectors etc. if the compression is not even, engine needs to come out.

this one time we had an Rx8 come in running on one rotor, it failed the compression test, so we went to order an engine, but Mazda told us to replace the ignition first. it was under warranty, so it was their money. we replace ignition and car fires up on both rotors and after running for a while it got compression tested again and it passed.

mkd

iTrader: (8)

Dale, I'm a dumb-dumb, you're right, it was the ISC.

How strange. I've never heard that before. The thing sounds like it's going to AFK itself.

Anyway, I didn't get to do another compression test today, but I did pull the plug wires off one at a time while it was running:

T1: no change in idle
L1: no change or very little change
LT: no change or very little change
L2: car stalled

I also verified that L1 & T1 were producing spark. So it would seem rotor #1 isn't doing a whole lot.

Will do another compression test soon...

DaleClark

iTrader: (55)

I'm going to have to show this quote to my wife .

Yeah hope you can get another compression test soon.

Dale

FührerTüner

iTrader: (5)

The engine will have lower numbers when its warmed up

mkd

iTrader: (8)

I thought it was the opposite?

DaleClark

iTrader: (55)

For your purposes I don't think it matters cold or hot. I'd just do a cold test. The results will tell you the information you need to go forward.

Typically warm compression is a bit lower than cold. Part of the reason why FC's were notorious for hot-start issues.

Dale

mkd

iTrader: (8)

Alright reporting back on this...

The mystery would appear to be solved.

First things first, I re-did the compression test (cold):

Front rotor: 71/69/64 @ 250rpm
Read rotor: 87/82/74 @ 250rpm

Not exactly good.

I talked to Chris @ Banzai (where the rebuild is being done) and he quickly identified what he thinks is likely to have caused my issues.

In the first post I mentioned that I had been having boost issues, that turned out to be the electrical connectors for the Charge Control and Turbo Control solenoids being swapped. This caused the turbo control door in the exhaust to not open. Which caused tons of back pressure. Which caused lots of heat. Which cooked my motor. Apparently the lower compression in the front rotor is common in this scenario.

I drove the car around with those swapped connectors for probably over 500 miles before pulling the UIM off and fixing the issue, and of course with my foot in it the whole time.

So moral of the story is, don't drive your car if it's not boosting right, or at least keep your foot out of it.

DaleClark

iTrader: (55)

I think the added heat with a motor that was long in the tooth would add up big time. Glad you could find the cause and share what happened, though.

Dale

IRPerformance

iTrader: (41)

Compression is way low. My guess is if you are using other than stock apex seals they warped or the springs sagged from the excessive heat. Both rotors should still fire though once it gets started unless the tune is that off.

FührerTüner

iTrader: (5)

At least you caught it before the engine blew. Hopefully you will have all reusable parts, save you some $.