Last night I get a call from a buddy, broke down on the freeway. Its a nice dry cold night, so I decide to take the 7 for a drive. I decide to get on it, and it goes fast and hard and smooth as silk.

When I backed off the accelerator I got a backfire, no big deal until I stopped to drop my buddy off. The car immediately died, was hard to start and the temps were higher than normal considering the ambient temp. I had to pump the accelerator to get it started and to keep it running. Idle was very rough and I had to get idle up to drive it. Once I was at cruising speeds it worked fine but sounded different and was running hot. I got on it a little and it seemed to accelerate not problem.

When I got it home, it would idle but very rough and there was a smell and smoke coming from what seemed to be the back of the engine. Not an oil smell or coolant smell, almost a plastic smell. The was also a new noise like a ch, ch, ch, ch. Oil and coolant levels were okay. The map sensor lines were intact and okay. Nothing visible from the top that seemed amiss.

This morning the car started like always but as it warmed up began to run sporadically. Vacuum level down to 8-10 at idle. Im thinking I probably blew a vacuum line or perhaps the intake manifold gasket??? The smoke and smell - the blown line touching something that is very hot?????

I spent hours last night reading post after post and have a few more ideas on things to check but would appreciate any feedback you may have. Tried to put the soundbyte of the engine noise on this post but it wouldnt attach. Will try again tonite.

The car has pretty much always run great with only minimal issues - all easily resolved. I have all the reliability mods done and just this summer turned the 40,000 mile mark on the original engine. Mostly stock but with downpipe, RB catback, slightly modded oem air box, efini y pipe, greddy piping, pfs engine mgmt, arc smic, hks twin power. Boost @ 10 - 11. Typically have about 16-18 vacuum. Water temp 185-210. Air / fuel all on the rich side.
Thanks
chuck

 

Check for loose/split MAP hose

 

First thing I checked!
thanks,
chuck

 

Try spraying starting fluid or carb cleaner around the engine bay (where you think the vacuum leak maybe) and see if the idle increases/smooths out. If so you have a vacuum leak in the area where you sprayed the starting fluid/carb cleaner.

Do you have a boost gauge, did it show normal boost ranges after this happened?
Do you have the ability to check the compression?

 

I do have a boost gauge, but I did not push it hard after the car died. The power seemed to be alright after getting up to cruising speed but I didnt want to push it to the floor after the incident. I have a regular compression tester, not sure if that can be used to check the compression though.
chuck

 

Yes you can,
http://www.fd3s.net/compression_test.html


and,
http://www.rotaryresurrection.com/
(click TECH link and then click COMPRESSION link)

 

thanks for the links. always thought that a special type of compression tester was needed.
chuck

 

jimlab was kind enough to host my sound byte file.

http://home.gci.net/~jimlab/images/M...gine_noise.wav

take a listen and see if this gives an idea of what might be wrong with the engine.
thanks,
chuck

 

^that is one strange sound

pfs engine mgmt <---pink 9 software??

torn LIM gasket would increase vac reading and idle...this sounds like a chipped/broken/damaged apex seal.

I'm sorry to say, this little purple engine eater ate my engine at 40k as well...I now have 50k on the clock with haltech for the last 10k miles, talk about smooth as silk.

 

No obvious reason to blame the engine management. I have run the PFS unit since 1996 without a problem.

 

sounds like one of the apex's is chiped, Does the speed of the sound increase relative to the speed of the motor?


its sound like if you were spining the engine over with no plugs....but in this case, one housing and one face.

 

I'd recommend a compression check.

 

just giving my experience...I ran that computer for 20k miles no problems until one day

 

Wow, that sounds bad.

I would do a compression check asap.

BTW: Do you have a cat? The reason why I ask is because I've seen (first and second gens) when those back up they cause similar symptoms to a blown motor (mainly sound and lack of power), aside from the good compression.

 

I am using pink 9 software.

The sound does remind me of rotor turning with no plug and speed picks up with the engine rpms.

Sound seems to be coming from the passenger side of the engine.

I have replaced the precat with a downpipe but the oem cat is still in place. If the cat was shot/clogged could that cause the high temps im seeing, the smoke from back of engine, and the weird smell. Would a clogged cat cause the poor idle.

Started the car again this morning with no problem and the engine runs fine with higher rpms but idle is bad and running 8 or so vacuum at 600-800rpm.

Will probably do a compression test tonite and get under the car to see if anything looks amiss from below.

thanks for input, keep the ideas rolling. I want to get all info I can and have a strategy formulated before disassembling the engine.

thanks,
chuck

 

Have you checked your plugs to make sure they are screwed in all they?

Yes. The exhaust may smell of rotten eggs or really bad.

This sound bad though. The vacuum being low is a sign of low compression and the fact that is runs better at higher rpm nulls out the cat idea (maybe).

Yeah double check to make sure the spark plugs are seated all the way. I've seen, personally, plugs back out and are just barely in the rotor housings. And from the sound clip it does almost sound like and engine turning without plugs in. Weird.

 

thats what I upgraded too when my engine blew...the timing is more aggressive and for some reason I couldn't control boost with that version S/W. Vent #'s would change even when I turned off the learn function...had to get a hallman's MBC.

 

The odor is not the bad cat sulphur rotten egg smell, its like some kind of plastic or rubber burning but not real strong and only after engine has warmed up. Does seem to be more of a rich fuel odor at start up.

I will check the plugs to make sure they are seated properly, but the sound is emanating from the passenger side of the car and may be between the uim and air pump. I took a nylon tube to my ear and tried to localize it but could not tell anything definitive.

chuck

 

I did retard the timing for the wot rpm range settings from 2-4 degrees and the air fuel is set rich over default setting thru the rpm range from 2-6%.

Havent heard any knock from the engine with my current settings.
.
chuck

 

Your ch, ch, ch, ch description was quite accurate. I listened to that sound bite and it sounded like your horses were trotting out from the engine...

Seriously, that sounds slower than anything I would expect from inside the engine - it sounds more like a belt noise once per belt revolution.

I wonder if something happened to the air pump (seized up?) that caused its belt to get a divot in it. Would a seized air pump cause a rough idle? It could cause a burning belt smell...

Running hot could be due to a water-pump problem - and a seizing water pump might cause a belt noise and smell, but that doesn't explain the rough running.

 

Damn, you said that before. I tend to miss minor but very important information sometimes.

 

I replaced the entire cooling system about 1.5 years ago, new hoses, new water pump, thermostat, belts, radiator etc. There is ample coolant in the system.

The belt that drives the air pump is okay, but I am wondering if a malfunction in the air pump could cause the symptoms Im experiencing. I believe there is a hose coming off it in the vicinity of the exhaust. Can they blow out with a short boosting run.

If the engine has a vacuum hose that is sucking air through a split, could it cause the ch ch ch sound? I believe that temps may rise with more air coming into the intake manifold through a blown hose or the hose nipple connection.

If an exhaust manifold gasket was blown, hot gases could come out through the gap and could create this ch ch ch sound but would it affect the idle stability? Those same hot gases could be heating something in the vicinity of the leak to produce the odor im detecting.

thanks again for the feedback, i will be getting off work soon and going home to explore some of these ideas. Im surprised that there hasnt been a definitive analysis of the symptoms and sound. oh well, keep throwing ideas at me.

chuck

 

Take a look at the EGR valve.

 

a3dcadman,

Last night, I had a little fun with a ferrari on the freeway. The car felt nice and normal afterwards (when I was at cruising speeds) and I thought everything was fine. Once I was out of the freeway sitting at a red light, I noticed the engine ran a bit rough. I pulled over to check things out thinking a hose popped off but everything seemed normal with the exception of that same exact ch, ch, ch, ch sound from your sound file. I couldnt pinpoint where it was coming from since it was late at night and I had almost no tools with me.

I did manage to remove the rear leading spark plug to do a quick poor man's compression test. The rear rotor didnt sound bad and the engine started up with just the front rotor (didnt disconnect anything :P). My vacuum reading is at 14-15inhg at 800-850rpms. The tach needle is pretty steady sitting at idle but the engine runs rough at idle. The engine gets smooth after 2000rpms when I rev it. Right before I got to my house, I gave it a little gas in first and the power seemed normal. I'm going to check the compression and everything else tomorrow if it doesnt rain.

 

Ive been out checking things out. Starts fine when cold, but hot it takes quite a few cranks to get it started. The ch ch ch sound isnt evident when its cold, only when it gets hot.

My damn girlfriend lost my compression tester. Dont know why women cant leave **** alone, always have to move stuff around.

cp