328 GTS Front cilinder bank not /bad working

When did it start?

Does it still have its exhaust analyzer tubes?

By the way. QV is a model designation term never applied to 328.

Also, you used the word "front" to refer to both banks. Going forward lets agree to call the bank at the rear widow "front" and the bank by the trunk "rear". It will prevent confusion.

 

I know what QV means. It was never used on 328s.

Can you pull all 8 of those plugs and get exhaust gas readings from them?

I suspect it will be found the exhaust gasses will be somewhere near correct on the rear bank and the front bank will be a mess.
The fuel system really will not do that. The ignition and cam timing will. From your description it sounds like the ignition is probably OK. My bet is despite what you saw the cam timing is off. The external mark are pretty meaningless. To check, the valve cover needs to be removed. When belts are replaced the front bank cams generally move on their own when the belts are removed and the marks are very hard to see so the belt gets installed incorrectly. It is very common.

If you measure the rear bank gasses and you see below 2% CO, above 12 % CO2, below 4% O2 and below 300 ppm HC thats all pretty OK.
I would expect low single digit CO2, high single digit O2 and 1500 PPM or more HC. Textbook case of a cam timing issue.

 

What was the compression on the rear bank?

 

Curious on a 512 tr what should the exhaust gases be ..sorry to hijack

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What I expected. But still not convinced it is the only problem. People get cam timing wrong then try to tune to make it OK. It just make a mess of things.

 

What I wrote above is acceptable for 328 precat. Not good, just OK.

512TR precat with 02s disconnected should be CO about !%, CO2 above 14%, HC below 200 PPM, preferably 100 PPM or so, and O2 below 5%, prob 2 or 3 %.

Measuring with 02 connected is just measuring a computer manipulated result. Motor should be in perfect tune without that. O2s are to correct near perfection. They should not be trying to correct a malfunction.

 

That exhaust cam is way way off. Fix that first.

 

So, when you write "12kg", do you actually mean 12 Kg/cm^2 (which would be a reasonable pressure value for this test)?

 

Seems off on Hydrocarbons ??? Not sure why

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Yes they are high. Typically caused buy a small cam timing issue. Could be burning oil but not common in a 512.

 

Funny..had two majors over the last 11 years ..two different people, different coast, same results .. fuel injection issue / possible ? Not burning oil that I see ..just the normal puff on startup after sitting a while

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There are other possibilities. Cam timing is such a common issue on these. At engine diagnosis school and engine rebuilding school we spent a lot of time testing for it and learning how to recognize it. With one cam it gets screwed up a lot. With 4 cams it gets screwed up most of the time. It is sensitive enough in cars of that period and so few know how to time them correctly it is very very common. Combine that with the fact so few are even convinced lining up the marks is just not good enough. At quite a few of the schools when they were still held in Italy one of the guys from the engine room taught us how to do it and it was the only thing they ever tested us on. In all those years with Ferrari they never tested us on anything else. Everyone in class had to time an engine with the instructor observing. An embarrassing number had real trouble with it. Then to make it worse Ferrari made a whole run of factory degree wheels that were mismarked. Those were distributed to dealers world wide. I cant help but wonder how many are still in use.

When I hear it discussed here I just shake my head at all the various incorrect methodology employed.

Also on that print out CO2 is not really optimal. Good, but not great. Of the 4 gasses read C02 is the single greatest indicator of efficient combustion. If I was tuning an engine and could only read one gas it would be CO2.

 

Brian,

IF I may ask,


What would a "Good" CO2 Number look like?


P.S.

Merry Christmas to you and Yours.

Mark

 

Depends on car. Modern are higher than old. On a 308 injected car 12% pretty good.14% better.

 

Thank you.