blazer1313

Ok gurus,

Senario is my friends FD has a severe runability issue after he honestly beat the crap out of it on a long trip. Before you jump to the conclusion that the engine is completely done, let me explain.

'94 FD Touring with 128k on stock engine. Has ebay downpipe midpipe and flowmaster 3" muffler otherwise stock. Has had the twins leaking oil for a while but thats it. He went on a 400 mile trip across the Cascade Mtns and to eastern WA and was on it a majority of the time and handled very well. On the way back he decided since the guy in front of him wouldn't get out of his way he would pull over to give the guy in front of him a few miles of room. Upon getting back on the road it instantly decided it had a loss of power below 4K. He then heard more than normal popping from the exhaust and then at a stoplight lots of blue, white and black smoke could be seen billowing from the exhaust.

Now it barely idles and it sounds like a lumpy cam usually not good. I then took a compression test..(pulled the shrader valve out and held the bleed button to read all sides of each rotor) and front and rear on all sides seemed to be around 85-92 psi if I could estimate. It has not lost any coolant and no check engine light. He did admit 50 or so miles before he pulled off the road he did refuel (always with 92) because he had ridden the low fuel light for a while.

Side notes:
He always lets it idle for a while before shutting it off
Recently had an oil change with 10W-30 non synthetic
Can still hear the turbo boost off idle through RPMS
Again, no check engine light
All plugs were black but had no coolant on them (one leading plug seemed to be more worn than the other???)

I can only guess at this point that I need to do a fuel pressure check to see if he has a weak fuel pump, or possiby a single stuck primary injector

Comments???

Link to video of how car now idles...

http://youtu.be/m3hDwbUQrOE

blazer1313

Oh....it has spark on all spark plugs also

skunks

unfortuantly i think something did let go after looking at your video. Odd that it happened after he had pulled over and not during a hard run but weirder things have happened. Actually perhaps not if you say he beat the crap out of it on a long trip and he didnt really know what boost he was running or what temp his engine was really at. Considering he doesnt have a water temp gauge or boost gauge, who knows what may have happened. could have just been from old age, these engines dont last forever. Does he still have the stock midpipe (just wondering, it doesnt really help to diagnose anything)? Too bad he doesn't have a boost gauge, I'd like to know what vacuum he is pulling at idle.

BTW: was there any particular reason why he was riding the low fuel light for a while?

Gringo Grande

iTrader: (97)

128k mile on stock engine? He should be thankful!

Ryan95

iTrader: (10)

Sounds like ****, but a motor making 85 psi on both rotors with even pulses is not blown. That's more than my motor makes.

blazer1313

no cats at all so straight pipe. He states that it never got hot (from stock guage). And yes it would be interesting to know what the boost was and now is. I can hook up a guage...I'm honestly more fimiliar with FB and FC's ...where is a good spot to plug in a vacuum pressure guage? Where is the service port to check fuel pressure? And riding the low fuel light only due to trying to find a quality gas station.

I was also amazed to see even psi. This car likes it rough! 128k and still tryin..ha!

Turbo II FC

iTrader: (14)

The stock gauge is useless. One time a buddys FD got to 115C which is deadly and the stock gauge was barely over the half mark.

Mr rx-7 tt

iTrader: (5)

Get a Mazda compression tester or try this trick. Pull the fuel pump fuse and the ignition relay. Pull out a leading plug and spin the motor over and listen for three even pulses. Then try the next rotor, do one at a time. If I still lived in Oak Harbor I'd come over! Grew up there as a kid...

blazer1313

I stated that I did a compression test and 85-92 psi on all sides front and rear rotors. Fuel rail service port, is there one??

Mrmatt3465

iTrader: (10)

I don't believe there is a fuel rail service port. If you would like to test fuel pressure you would have to tee into the line.
The compression test absolutely yielded 85 ish psi on ALL faces and not maybe 2 of 3 faces? TYPICALLY running a cat less exhaust on a stock FD with no ported wastegate or PFC is a big no no. That compression seems pretty low as I think the minimum the FSM says is good is 85. If your plugs don't have oil or coolant on them than I might suspect a coil as the next culprit.

skunks

he did mention that he was getting spark on all 4 sparkplugs, would a bad coil still spark?

Mrmatt3465

iTrader: (10)

Hehe I absolutely skipped right by that post. Oops :p the reason I suspected a coil is because my buddies rx8 ran like that when his coil died on him. It was pretty hard to start and idled low and lumpy.

Mingaa

What does the smoke smell like?

skunks

from the video, it looks like white smoke which would lead me to believe its coolant. I always though blue was oil and black was too much gas.

blazer1313

There was never a side that didn't rise to 85 psi from compression. I too would think white smoke is coolant but it hasn't lost any. The color of the smoke honestly depends on what rpm its at. At idle cold, its more black. If it were a diesel I'd say we have a bad injector or injection pump but heh its not.

I tried to count the combustions in the exhaust before it cycled again but I can't. I know it should be 6 but it sounds like 4 or 5..

What would a blown oil seal or coolant seal make it act like?? But again, the plugs weren't wet with coolant. Though on the front rotor, the trailing and the leading plugs weren't real tight and you could see oil coming out from around them...

Explain to me about the no-no with no cats please??

Mr rx-7 tt

iTrader: (5)

I have had many people come over who had done the remove the shrader valve test and thought they had good compression, they didn't when using the Mazda compression tester.

ZE Power MX6

iTrader: (157)

I would test your injectors, remove both rail and jump the fuel pump and see if they are leaking. My car did the same thing last year, I drove it hard for a little bit then out of a sudden it was running on one rotor after a stop at the restaurant, it was blowing white smoke all over the place.

At first I Thought I blew my motor, but with a rotary diagnostics compression tester I confirmed that I have over 100psi on all faces. So I decide to tear it apart and test the injectors, turns out one of my secondary was stuck open and flooded the front rotor the entire time. Install a spare set of rail, then went through the de-flood procedure and the car runs fine now.

Mahjik

iTrader: (1)

The FD uses a programmed ECU map. Therefore, if he increased the airflow with a midpipe but didn't increase the fuel with an aftermarket ECU he could have run into a lean condition and had pre-ignition. Also, was the engine cold for the compression test?

The car doesn't have a boost/vacuum gauge? If not, borrow one and hook it up just to see where the vacuum is at idle.

Mrmatt3465

iTrader: (10)

I believe compression is supposed to be done on a warm engine. If you had oil around your spark plugs on the front rotor that could be a failed oil control ring.

adam c

iTrader: (2)

I would start by replacing the plugs. Sometimes the simple solution is the right one.

blazer1313

Thanks for all the replies guys! As a boat and moderate car mechanic I'm suspecting a fuel issue. And I can totally follow ZE Power MX6's idea as one to try before I condemn the whole engine.

For a 128k mile engine I can also believe the failed oil control ring. I'd like to salvage and make it run again if possible then say, "She will live, but she doesn't have much time" lol

Easiest thing first... I will hook up a vacuum guage....what are the #'s I should be looking for a healthy engine at idle?

I had run the car for approx 10 mins before the compression test was performed.

I would imagine there's a writeup on how to port the wastegate? And if you port the wastegate aren't you going to increase the boost? (Sorry, for the noob question. Can't you tell I'm a NA guy?)

Mrmatt3465

iTrader: (10)

I don't believe there are any band aids for a faile oil control ring. Have you checked your intake elbow for gratuitous amounts of oil? That could indicate a bad oil seal in the turbos if you'd like to check that. If you would like to check your injectors, I believe most people tag them with 12v (please look that up as I'm not 100% sure I think I recall some people using 9v batteries sometimes) and listen to the injector click when you do it. We were all noobies once Porting your wastegate allows more exhaust to leave the turbine housing for greater control of more flow through the housing. When the wastegate hole is too small, it is insufficient at slowing down the turbine wheel to proper boost. By porting it and making it larger it allows more exhaust to escape and maintain your desired boost level as opposed to creeping higher and higher as rpm increases. AFAIK, porting your wastegate should not increase boost. Especially if you have a feedback style boost controller(which most are now a days).

Ryan95

iTrader: (10)

Above 10in or vacuum at idle is an engine that should run fine, albeit one that's maybe hard to start and not exactly healthy. A good solid motor should be in the 16-18 range.

Porting the wastegate is actually a way to prevent boost creep. The wastegate is too small to get rid of all the excess exhaust gasses, so you get too much boost.

ZE Power MX6

iTrader: (157)

You won't get good vacuum reading if you have a bad injector like me, it'll read low but just make sure it is stable and not bouncing up and down. Mine read steadily at 10inhg at the time, and now it's back at 16inhg.

stevensimon

iTrader: (11)

probably have an injector leaking pretty bad or is flat out stuck. i had this issue plague me after a decent overhaul on my car. i swapped out unknown condition injectors for ones i had serviced. car ran like crap (a lot like this one seems to). i checked everything except the injectors. on a whim i put the old ones back in and it ran like a million bucks.