Juan

iTrader: (28)

I didnt hear the ch ch ch sound when the engine was cold either. I havent done a compression test either since theres no one home to help me. I guess I'll do the poor mans compression test since I can do it by myself for now.

darkphantom

iTrader: (2)

SPARK PLUGS/ Batter cables/wires ALternator maybe?



maybe some ignition breakup

darkphantom

iTrader: (2)

i had close to a similar problem. one was the idle screw was mess up.

also one of the hoses got loose and had caught dirt in the hose. for the idle

DaveW

No, a clogged cat would not affect the idle unless it was almost totally plugged, in which case you would have almost no power at higher throttle openings and higher revs.

batmanmoto

Sounds like a bearing not turning smoothly,air pump?The smell and slight temp rise can be caused by the cat but that noise...Don't hold me to this but just a quick check,is your clutch system in the vac pump still working(does the centre stop spinning at med to high revs)?The bad news is that it could be a seal,and yes at only 40K.If the car spends long rest's between use(1-2weeks)parked up! I wish you luck and hope it's something externial.

a3dcadman

iTrader: (1)

the plugs, wires, cables and twin power less than 1 year old.

the gf found the compression tester finally. tonite i will run the comp tests.

another thing ive thought about was the prominence of the ch ch ch sound after the car warmed up. still have not been able to isolate the area that is producing the burning plastic kind of smell yet.

still waiting on input as to whether blown vacuum lines and/or intake manifold seal can create a very lean mixture and consequently a lot more heat.

car doesnt sit most of the time. its hard not to drive it.

i thought i would share a note from herblenny in response to my inquiry:

[quote]
herblenny is Offline:
Re: question re: blown apex seal
--------------------------------------------------------------------------
Chuck,

without acturally seeing the car, its hard for me to say what is wrong.

by reading your thread, it sounds like chipped or blown apex seal.

So, can you increase the idle and does the shake disappear when you do so??

I'll tell you couple of things to look for and if all syptoms fit, then most likely you;ve blown your engine.

1. engine will shake horribly around 900-1200 RPM.
2. Engine smooths out 2000+ RPM
3. take one spark plug off from front rotor and see if you could hear a skip in compression. check the rear and do the same (either take the ingnition relay or take the spark wires off.).
4. Take the turbos off and see if turbine is damaged due to apex exitting the engine.

Good luck! [quote]

[quote]
Originally Posted by a3dcadman inquiry to herblenny
There have been a number of posts addressing the problem Im experiencing, but no one has seen the same symptoms collectively that Im dealing with. Ive read quite a few post of yours with regard to blown engine apex seals. I believe you may be able to provide me information or further insight regarding my dilemma. I have a sound file to scrutinize within the thread. I am currently in the process of going through a checklist of items to look at and running some diagnostic tests. Here is a link to my thread.

https://www.rx7club.com/showthread.php?t=480478

thank you for any feedback you may have for me.
chuck [quote]
__________________

thanks herblenny and everybody for your input - i will let you know the result of comp test.
chuck

a3dcadman

iTrader: (1)

I finally got my compression test completed. Here are the results of the 2 tests for each rotor. I ran both of the tests twice through for both rotors to confirm my initial readings. The battery was fully charged prior to testing.

FRONT ROTOR
1. this test used the compression tester with the pressure valve out. the pulse from each lobe was even and consistent for multiple engine revolutions with no skip in rhythm evident. each pulse produced approx 75 psi consistently.
2 . this test used the compression tester with the pressure valve in. total accumulated pressure for all three lobes for multiple engine revolutions was approximately 75 psi.
3. got the same results both times through the tests.

REAR ROTOR
1. same procedure as front rotor but with 100 psi for each pulse.
2. same procedure as front rotor but with 100 psi accumulated pressure.
3. twice through the tests yielded same results.

Any insight as to these results and numbers. What could cause the different readings from front to back (75 psi front / 100 psi rear)?
Is the front rotor more prone to failure?

The plugs looked fine other than a dry black carbon deposits buildup No wetness or electrode deterioration.
Ive still got some more things to check out.

chuck

mdpalmer

iTrader: (24)

I had a compression test done on my motor recently, also with lower readings on the front rotor. The motor actually ran pretty good and held good vacuum (for a street ported motor; 14 inHg or so @ idle). Results:

[The results are in kgf/cm^2, while the numbers in () are in psi:
rotor #1: 4.9, 4.2, 7.8 (70, 60, 111)
rotor #2: 7.2, 7.0, 7.2 (103, 100, 103)]

A person from Banzai RAcing chimed into a thread I made:

"Guidlines for diagnosing engine internals based off compression readings. Obviously these are not set in stone.

3 even bounces of 85 PSI or above is GOOD. Readings above 110 PSI is GREAT!
3 even bounces of less than 85 PSI: indicates that motor is tired, and indicates engine should be rebuilt before causing damage to rotors or rotor housings.
2 high and 1 low: indicates problem with side seal (stuck, cracked, broken, etc.)
1 high and 2 low: indicates problem with apex seal (stuck, cracked, broken, etc.)
NO bounces: either incorrectly installed guage or destroyed rotor and housing.

What we have noticed is that when the front rotor has uneven/no compression that 9 out of 10 times the pulsation damper is leaking fuel, causing fuel starvation to the front rotor."

You can also get this information from their website (www.banzairacing.net). Man I wish you luck on your motor. I'm in the market for a reman/rebuild right now....

nopistons94

usually the rear rotor is prone to failure because it gets a lot hotter back there and harder for the oil to lubricate it

Juan

iTrader: (28)

I did a compression test on the engine today. While I waited for my ride to buy a compression tester I did a poor mans compression test. Front and Rear rotor sound great. The rear rotor had one pulse of air that was slightly stronger but overall it sounded good. Once I got my compression tester, I tested both rotors with the engine cold. Heres my numbers:

Front rotor: 90, 90, 90 psi
Rear rotor: 90, 40, 40 psi

I tested each rotor twice and got the same results both times. My vacuum reading is 15-16in at 850rpms with the engine in its current condition.

#1 and #2 are accurate descriptions of my engine except my engine doesnt shake horribly. The engine just feels rough at idle and the car feels pretty much the same power wise. I just wanted to share my similar experience as a3dcadman and not highjack his thread.

Juan

iTrader: (28)

One more thing...

Is it possible for a seal to get stuck just out of the blue?

a3dcadman

iTrader: (1)

I found out where the excessive heat and odd smell is coming from. Its my catalytic converter right where the pipe from the engine joins the side of the converter. It was glowing red in the subdued light under the car. Never noticed this before, so Im guessing that it is a result of this current issue with the car.

Feedback anyone?

chuck

tcb100

Could be the result, too much unburned fuel getting to the cat, or if the cat is clogged, it could be the cause.

mgoddard1

That sound bite seems to have a pulsating sucking noise in it similar to cranking the engine without the spark plugs in. Maybe you have an original paper LIM or UIM gasket and it blew out?

The glowing cat is probably due to raw fuel being dumped into the exhaust system.

a3dcadman

iTrader: (1)

As far as I can tell, the sound is localized in the area of the LIM / UIM. Could all the symptoms Im experiencing be a result of either or both of these gaskets blowing out. There is a high probability that the gaskets are the OEM paper ones. Typically, what would cause them to blow out?

Would a faulty pulsation damper affect the catalytic converter like Im experiencing and cause the rough idle and engine stalling as well?

quote from banzai racing:
"What we have noticed is that when the front rotor has uneven/no compression that 9 out of 10 times the pulsation damper is leaking fuel, causing fuel starvation to the front rotor."
(www.banzairacing.net).

Im trying to maintain an optimistic attitude on my engine problem. I am hoping that it isnt a apex seal. With some of the recent input pointing to other potential sources for the problems and my compression test results not conclusively indicating a totally blown engine, my strategy for resolving this mess will include new vac lines and the appropriate gaskets for the hose job. Anything else I should get before diving in? Contingency planning to help keep things rolling.

to all again, thanks for the info.
chuck

mgoddard1

Just being 10+ years old is enough for the original paper gaskets to give out. At some point they switched to all metal gaskets for this reason. Also a leaking gasket can cause fuel starvation as well but if the FPD is original you might as well replace that too while you're in there. If the hoses in the rats nest are original you might as well check them too and also verify all the check valves and solenoids are still functional. Ray Crowe at Malloy Mazda seems to have the best prices for new metal gaskets and a FPD. If it's the LIM gasket that blew then you'll have to pull the turbos out which will make your job about 3 times more difficult but you still can do it without pulling the motor.

tcb100

This should be filed under "For What It's Worth" because that sound is pretty strange.

Earlier you said the problem started after you dropped off a friend and the car died. You also said the car started normally but as it warmed up, it idled worse and worse and was running rich. The glowing cat says there is a lot of unburned fuel getting to the cat.

Since the problem surfaces when hot, what is going on occurs when the car is warmed up and in closed loop. Have you checked your o2 sensor? If it were sending a false lean condition, the ecu would be “correcting” and adding too much fuel, possibly leading to a hot cat.

Second, a bad coolant temp sensor would also supply more fuel than it should when the engine was hot. It should be sensing a warm engine and reduce the enrichment it supplies at start-up.

I think your compression check leads away from an internal problem. If the car starts normally, the odds of a blown motor are pretty low. The one engine I heard with blown seals sounded wheezing during the start-up & was very hard to start. A blown coolant seal typically has the start-up problem too. The sound clip just does not sound to me like anything internal but I have a heard a very small sample of blown engines. I measured some 5s and 6s and still ran an 11.69.

If your plugs are dry, you are probably not dealing with a leaky injector & if they are not fouled, probably not an ignition problem. And your coolant system is practically new.

Your air pump sends air to the engine at start-up when the engine is dirtiest. The air helps to fan the flames and get a better burn. After the engine warms up it send the air to the air pump to aid the cat & with a red hot cat you appear to be getting more than enough air.

The EGR is only supposed to function at cruise, delivering inert exhaust gasses to reduce temperatures and NOX. It should be closed at start-up and idle. If it were open you would get a rough idle and stalling and backfiring because the burn rate of the gasoline has been slowed down yet at cruise the engine would function normally. That would also account for unburned gas in the cat, leading to a hot cat.

So of everything I heard so far, I would consider the EGR. But again, for what it's worth.

a3dcadman

iTrader: (1)

I had just gotten on it for an 1/8 mile stretch and when I stopped the car just after that run, it immediately died. At that point it was extremely difficult to start. When it did start, I could not keep it idling and had to pump the gas to keep it going. The next day after sitting all night, it started fine and as it warmed up the idle got progressively worse and the ch ch ch noise became more pronounced.

The o2 sensor was replaced a year ago and I have not checked it yet.

Thank you for a very concise and thorough analysis. One more thing I wanted to mention, at startup when cold there is a very strong exhaust smell as well but I cant see where it originates.

Is there a testing procedure for the EGR?

I have pretty much concluded that I will be doing a complete servicing of the engine down to the LIM. Tomorrow I will be ordering parts from Ray Crowe. The silicone hose kit is already ordered. Someone had also mentioned replacing turbo coolant hoses. Any other suggestions for parts to order. Id rather do it once and do it right rather than half assing anything with respect to my 7 because I really dont want to have to mess with it again. Wonder if there is a list of suggested or recommended parts to replace with this type of engne servicing?

thanks again.
chuck

a3dcadman

iTrader: (1)

Can a catalytic converter be inspected visually to determine if there is a problem ie. clogging etc?

chuck

tcb100

You can hear it. It sounds "muffled" & it "feels" plugged. And you won't make much boost. That's a key indicator if it's plugged.

If you take it off and shake it you will hear stuff rattling around. Typicaly it's those loose pieces that get jammed up and block the flow.

RotorJoe

Pull the cat and take a look. Hell at that point start the car and see if anything has changed (besides the loud exhaust).

a3dcadman

iTrader: (1)

Wan,
No problem re: hijacking the thread. Your symptoms closely match what I am experiencing. I want to get as much info as possible from all sources. Have you started taking things apart yet? As soon as my parts arrive, I will be starting the disassembly process. Let me know what you find.
chuck

RotorJoe

Yes, although yours maybe blown. Try a few of the ideas on how to unstick a seal (water or ATF trick depending on what you like, search) Or just rev (cycle through the 2-3k range) it some and/or go through a few engine decelerations (down a hill) at 3k or so. Engine braking puts the motor in heavy vacuum and may unstick some seals that way (but I think I've had them stick once in this case also).


Good Luck

Tim Benton

iTrader: (1)

Did you ever try the suggestion posted earlier about spraying starting fluid around the engine, trying to stay clear of the intake filter?

Tim

Juan

iTrader: (28)

The compression test was the last thing I did to the car. Since the rear rotor had low compression, I kind of threw in the towel until I got my rebuild. Unfortunately my work schedule (10hr days) doesnt leave me much time to work on the car until December. I'll definately keep an eye on this thread and let you know if I find anything usefull while working on my car.