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YOUR RESEARCHBenefits of Engine Compression Test, spark plug recommendations
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Run bosch plugs
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Benefits of Engine Compression Test, spark plug recommendations
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Leading evidence: 'Run bosch plugs' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'fsi work and not the ngk's' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check cam deviations, fuel trims' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Benefits of Engine Compression Test, spark plug recommendations
Use by top engine builders
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Blow-by tests are a " black art" only used by Top Engine Builders.
Benefits of Engine Compression Test, spark plug recommendations
Use ngk's in all my cars since my forever
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Benefits of Engine Compression Test, spark plug recommendations
Use three makers
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Used all three makers for coils and plugs for my Pcars with zero issues.
Benefits of Engine Compression Test, spark plug recommendations
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Hi everyone. Due to my car approaching 98000 miles I want to check the engine compression. It�s a cab le throttle 3.4 99 coupe. To me car runs fantastic, no smoke barely uses any oil and during the last three months I�m averaging about 22.5 mpg. Yes I get to drive it on the highway normal is 75-80 mph, but on a bunch of straight aways once everything is up to operating temp, I drop to 4th, wot and take supersonic for a bit 125 mph or so. Also I do accelerate it hard at some stop lights, merging into highways etc. Anyway, I want to run the durametric again to re check cam deviations, fuel trims. Assuming all this checks fine again as it was checked in April, I would like to check engine compression. What number should I be getting and on this particular engine how useful will that info be. A final question. Spark plug recommendations.
Zbomb recommended this ones, any thoughts about NGKs?
I'm not sure it matters for a street machine. I put the NGK's in mine. I've used NGK's in all my cars since my forever. The next day there was pro-Bosch thread. Car ran just as well as it did before. Now the engine is an FSI 3.8L with the same NGK's and it runs awesome. But that's likely the FSI work and not the NGK's.
Flip a coin?
Hello! It sounds like we use our machines in a very similar fashion. What you described is exactly how my 996.2 runs and drives. Same gas mileage too. Mine is apart right now for lots of hang on parts, i.e. fuel injectors, AOS, SAI, and vacuum system. Basically all the stuff that bolts on to the top of the engine.
I am running Bosch plugs from FCP. There is about 6 or 7 thousand miles on the current plugs. Since FCP offers a lifetime warranty and I've got them out they are getting changed. I agree with sentiments above that for street use any quality plug is fine. Just keep changing them out.
I"m sure someone will chime in for the compression numbers and I think it's a good thing to do. sounds like you have a base line reading to compare to. If you have a way to do a compression test I would encourage you to do it and keep track of the readings. If they get too low it points to wear on the engine.
This morning I was actually looking at doing a leak down test. It's more accurate and allows you to see where the leak is coming from such as valves or rings. One thing I really enjoy about this car is that I can learn how they built them. It's a different way of thinking about cars and I think it's enjoyable. That said, I'm learning about leak down testing.
I found this at Summit.
https://www.summitracing.com/parts/otc-5609
Best,
Jason, Zbomb said the same about the plugs from
fcp. I�m just learning a bit more about these engines. Anyway I have an awesome 33 year old mechanic that knows quite a bit about these cars. Anyway, since I�m retired I enjoy scheduling with him go to his house drive the car, listen to music and last time in addition to beers I took some ribeyes and sausages to grill. I used to wrench but I prefer and want my guy to do most of the work, I also try to get him additional work from fellow PCA members. I told him that if he needed capital I am there as his partner. He also works for a p shop 3 days a week. Thanks for the leak down suggestion.
The problem with compression tests, leak down tests, and blow-by tests, is that Porsche gives no specs for new engines. And no one really has any interest in collecting data on new engines ( every is one too busy with other things) . So the only time the tests are done is when there is a suspected problem, at that time the "rule - of -thumb" is used to diagnose..
The "rule-of-thumb" on compression tests is a 10% difference from the highest to the lowest value ie if the highest is 160psi the lowest can't be less than 144psi....
Same goes for leak down tests, none will be 0 leak down but you want a low and even reading across all cylinders.Opinions differ on what is acceptable , but all agree that no large differences are accepted.. Leak down tests are most useful in "locating" the source of a failed compression testie whether it is rings , exh valves, or int valves.
Blow-by tests are a " black art" only used by Top Engine Builders. I tried to get a data base for typical blow-by values on m96 engines of different mileages, but only got 4-5 data points from the community. But still blow-by values are the best there is for engine health evaluation ( if you know what they are).
FWIW :::theoretical compression valve for an M96 3.4 would be 14.7 (Atmospheric pressure at seal level) X 11.3 (compression ratio) = 166psi
I'm 8000 miles away from my receipt for the plugs, so I can't be 100% positive, but I think these are it.
https://www.ngk.com/ngk-3199-bkr6equ...und-spark-plug
Good luck!
OP - Bosch and Beru 4-prong are OE (with those plugs made in Europe). NGK are also just fine. Used all three makers for coils and plugs for my Pcars with zero issues.
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