fd3s_rx7

iTrader: (13)

Okay I'm two hours away from my house and in need to come back home and I'm at my cousin house right now stuck.

What happened was, I WOT my FD up to third gear, and while we came down the freeway and came to a stop on a stop light, my car just started shaking like hell...and vacuum was like at 10. to 11. really low vacuum. But when drive the car and rev up, the motor doesn't shake and also runs normal when driving. Just that when come to a stop, it'll shake like hell, well sort of and it'll just vacuum really low at 10. The other thing I notice was strong gas or fuel odor on the back of the Upper Intake manifold.
So far what I did was check hoses, clamps, and vac hoses. Seems to be okay. And next was compression test. What I did was run the car to it's normal heating temp. and test both of the spark plug on both of the rotors (Trailing) both results at 100psi. consistency. This is obiviously good Compression. Now I'm stuck at the point of what could it be. The car doesn't smoke at all. No white smoke, but I do see black smoke when reving the engine. But that's because prob. running rich. No blue or white smoke.

Engine shakes, miss fire (popping) at exhaust tip, and strong fuel odor at UIM...

Compression at 100 psi on both side on both rotors.

Thanks Guys

Azaka

sounds like the line to the map sensor came uplugged. double check that line.

fd3s_rx7

iTrader: (13)

Oh yeah, turbos are 99 spec. efini turbos, and they are fairly brand new. Just installed last week. Still build boosts and turbos still spools perfectly.
ECU is Pettit Racing, been remapped to run rich. And tune to run 13 psi. Have this ECU on the car and boost 13 psi for 30,000 miles now.

Any idea before I take off my Upper Intake Manifold.????

thanks

BigIslandSevens

iTrader: (4)

Take some carb cleaner spray and spray it around the LIM gasket. The one that connects the LIM to the engine block. It sounds like you may have blown that gasket out.(When you spray the carb cleaner the idle rpm's will most likely go UP, do to extra combustable fluid in the engine)

What year is your car? The 93's came with a paper gasket that is famous for getting hard and brittle and starting to leak. The new updated gaskets are metal. If you get the rpm's to fluctuate then to replace the gasket means removeing the turbos. It is also a good reason to do a hose job, replace the FPD, and other goodies while your in there.

FWIW: Ray crowe @ Malloy Mazda has a great manifold gasket kit that includes all the manifold gaskets except the turbo to exhaust manifold 2.

Also someone is bound to say it so I will too. Check your map sensor hose. The one on the firewall by the brake booster cylinder. If it pops off some of the same symptoms exist.

EDIT: See...someone already said it. I think that is the second most posted remark besides "Glad your OK, and it worked out in the end."

fd3s_rx7

iTrader: (13)

yeah,
map sensor was one of the first I checked, vac lines is still connected to it. Still good.
I will try that Carb. Cleaner spray thingy..

fd3s_rx7

iTrader: (13)

okay,
just finish shooting compressed thru the brake booster to see if I have any leaks. The only leak I'm having are from the Intercooler Pipe that is connected to the throttle body, and the Air Pump also has a fat *** leak.

Fix the Intercooler pipe by slapping on some Gasket maker but the engine still shakes and miss fire, or back fire, like poping. and when rev, black smokes flys out the tail pipe.
Damn, I'm getting really frustrated... Can't find what is wrong with the car.

fd3s_rx7

iTrader: (13)

Oh yeah, one more thing I forgot to mention, when I did the compression test, the spark plug are wet. Oil seems to be dumped around it. But I did, did another compression test on both rotors (trailing plugs) on both side, and same results. This time 95 psi consistant on both side. Maybe drop 5 lbs because did it when engine is not warm??

But yep, Now come to think of it, Compression is good, No White Smoke, Did coolant check by using a funnel to see if bubbles or boils, result came out good, no bubbles.
Car still shakes, vacuum still at 10, and blows black smoke when rev. But seems to be normal when driving and revving past 1.5 RPM. I'm thinking it has to do with fuel. Am thinking could be Injector got Stuck, or I prob. shot an injector. My Primary Injector???

jspecracer7

Change your plugs. Wet plugs = no spark.

LT1-7

if your car idles without stepping on the gas and your vacuum is still low, that is a good indication you may have a broken apex seal.

If it were a vacuum leak your idle would have shot up high, very high

jspecracer7

A broken apex seals also means low compression....100 psi on all six sides isn't low compression.

shawnk

If it is fuel then a WB02 would tell you. How about using the commander function where you can change the fuel entire map with one setting? Just lean it out alot and see if the idle corrects. That cant hurt can it- going lean at idle? I guess if the injector is stuck completely open that wouldnt help. You could switch the injectors and see if the wetness changes rotors.

weaklink

sounds like the symptoms i have. someone told me that i have a stuck side seal. car still starts and runs hot and cold. idle lopes like a v8 witha cam, lots of fuel smell out of the exhaust (no cats though), but still runs strong, drives fine above idle.

fd3s_rx7

iTrader: (13)

yep,
just change my plugs yesterday too.

But still same symptoms...

LT1-7

How do you know it was 100 on all 6 chambers? Not many people have compression testers made for a rotary. If it were just a regular compression tester, you could still get a good reading but have a broken apex seal. As long as one of the seals are keeping compression, the tester will show the highest reading

gdnimr0d

iTrader: (4)

my car did that ....one night it happened vacuum got real low and backfired and shook like all hell at idle....i thought i blew an apex seal...but i was wrong...what i did to fix it was i just revved my car all the way to red line and then right as the car was coming back down to idle it was fine....never really found out what the problem was but sometimes **** in the engine needs to be spit out the exhaust with high rpms and sometimes seals need to taste high revs and lub up...well try redlining it...peaceout and good luck

93BlackFD

lets hope he doesn't know how to use a compression tester and left the check valve in....

fd3s_rx7

iTrader: (13)

I read a thread about that check valve. Was wandering where that check valve really is...
And tell me whether I did it wrong or not???

1st: Took off all four spark plug wires
2nd: Took off one of the trailing plug
3rd: Screw n Compression valve
4th: Crank the engine,
5th: Crank the engine till maximum compression number shows.

that's what I did on four plugs and all came consistant to 100 psi..

Thanks

sirjury

remove the valve in the end of the compression gauge. it is the same valve found in your tire valve stem. if you dont remove the valve the reading you are seeing is the highest of the 3 chambers of the rotor being checked. you only need to check the leading plug holes. there is a very cheap tool sold at most auto parts stores to remove the valve from tire valve stems, it will work the same on your gauge. when checking the compression the needle on the gauge will pulse. each pulse is one side of the rotor. the pulses should be equal and consistent good luck

BigIslandSevens

iTrader: (4)

I agree with most of this except that it is the Trailing plugs you remove and check the compression thru.( the top plugs) I never have tried the leading holes so i do not know if there is a difference between the readiings.

I have always tested per the Factory service manual.Pg. c-9, and c-10

alberto_mg

how much boost were you running?

and what are your mods?

smg944

iTrader: (34)

seems like a leaky injector or stuck injector. had that problem with my turbo 2 and had similar symptoms. i would check that next.

fd3s_rx7

iTrader: (13)

yeah, cause I went thru testing everything I could think of already. Rewire some ground, Checked again for leaks (found none), did a compression test yesterday night again, and result came to 95 and 93 consistant on both of the trailings. No White smoke at all... So this I think it has to do with fuel, but not sure. Will take off that manifold next week when I have time.

thanks for all the help and comment guys....

93BlackFD

check valves....you're still using it, remove it

fd3s_rx7

iTrader: (13)

My mods are:

Pettit Ecu that was remapped and tune to run 13 psi
99 specs twin
HKS Mega Flow intakes
HKS Dragger Exhaust
3in Down Pipe
Blitz SMIC
AST
HKS spark plug
Greddy Pulleys

LT1-7

First off, do a compression test the right way. It's very easy to do or have done. From there it will be cake to find your problems

I still don't think it's an intake leak or an injector leak. Like I said before, if there is any air leak at all within the intake manifold, your idle will shoot up high.

It could be a leaking injector but you said your idle was still high. A stong idle should still pull good vacuum