compression problems....

[Anonymous]

hey,
Have had the car towed to get checked out after the problem with the water temp sensor (being the wrong one)then putting the old one back in and the car not starting, as some of u would have read in my old post..
well compressions were 10psi in no.1 50psi no.2 30psi no3 35psi no4.
so they did a leakdown test, and there was no leakage that was regarded anymore then u would normaly have, except outa the valves.
so they put some special stuff in which should help raise compression, and then rechecked and all 4 cylinders went back to 160 on each WHICH IS WERE IT SHOULD BE. so they took the cam cover off just to check clearances and all where spot on, took it for a drive and was ok, did another compression test and it wasall at 160. now they will wait till the morning when the engines cold and do another compression test to see that it ok...

they said that the engine was flooded full of fuel and there thinking that it has been forced behind the valves or somthin and kept them open (dont realy remember what he said)

he said that after a 5 min drive my plugs where totaly black again, indicating still a lot of over fueling..
BASICLY THEY SAID I NEED A AFTERMARKET COMPUTER TO FIX THAT AND THAT THAT WILL FIX THE PROBLEM WHERE THE POWER DROPS DOWN 25 KW ATW WHEN THE OIL TEMP HITS 90DEG,,,
THE COMPUTER THEY WANNA USE IS A HALTECH BUT THEY GUNNA MAKE IT TO A PLUG IN INSTEAD OF WIRE IN,$2500 for it and fitted and tuned if it fixes all the problems and if it doesnt i get it for nothing.....
YOU THINK THEY COULD TUNE AROUND AND COVER UP PROBLEMS THPOUGH????
they want $4000 bucks for motec so thats too dear...
so anythoughts on how my compression could fuck up that much, and is there anyother ways to check that my engine ant goin to go bang before i buy a computer....????

SORRY FOR SUCH A LONG POST....
THANKS LUKE....

 

[geetee]

Fuel Pressure regulator playing up or injectors stuck open??

I've not heard of flooding an engine with fuel holding the valves open - but then I don't know much :?

What was the 'special stuff' they put in to raise the compression again? Chemical Metal to fill the holes in the top of the pistons :lol: ?!

What other mods do you have on the car?

Cheers
GeeTee 8)

 

[AJ4]

Sounds like you have two problems, running too rich and also low compression.

They are talking complete horshit, a fuel ecu is not going to fix what is apparently a definite fault - it could possibly be a hole in the diaphram of the fuel pressure regulator, it happened on another nissan I owned ( same regulator ). Fuel was leaking into the vacuum line from the plenum chamber, so the engine was just sucking in fuel directly from the fuel line and not through the injectors. The symptom was running extremely rich ( black plugs ) and eventually it got so bad the cylinders filled up full of petrol to the point where the engine wouldn't even turn over ! Easy to check, take off the vacuum line to the fuel regulator and see if there are any signs of petrol in it. Try blowing through it to see if the diaphram is bust.

Second problem, compression, sounds like you have a broken or worn ring. If the compression is low, its normal to put a little bit of oil in the cylinder and try again. If the pressure comes back up, it usually means that pressure is leaking past a worn ring and the oil is temoporarily sealing it. It has nothing to do with the valves, if the pressure didn't come back up after the oil and was still the same, only then I would suspect a valve.

 

[Fast Guy]

Strange one. :? It don't make sense to me
Is this a reputable garage?

You had low compression that was leaking out of the valves????
Yet putting special stuff in the cylinders(engine oil normally) raised the compression, which means your piston rings are stuffed. If it was the valves the "special stuff" should make no difference.

I don't see how the fuel could keep the valve open, it would just get squirted out until the valve closed then it may do some damage when a hydraulic lock occurs (if there's that much fuel in the system)

 

[Anonymous]

Ok got the car back and so far it seems ok...
the compression is still 160 on all 4 which is great.. they have done the following on it.
-compression test,
-cylinder leakage test. therewas no more leakage past the rings then u would normaly expect.
-checked valve clearances
-removed checked and cleaned injetors
-decarbon intake maifold and upper cylinder and pistons(fucking cost $400bucks just for this one, the fluid they use they said cost 200bucks alone)but they said it comes up like new.
-checked fuel pressure regulator. its fine, but they said something about the vacume on it being weaker then normal
-replaced plugs as the hks ones were so rat shit...and would even clean up.
-and then did a normal service on it.
THEY ARE THINKING THAT THERE WAS A HEAP OF CARBON BUILDUP AROUND THE VALVE AREA AND THAT WHEN THE CAR GETS UP TO CORRECT TEMPS(WHEN I LOOSE POWER)THAT THE VALVES ARE STICKING.AND THATS THE HORRIBLE STENCH U CAN SMELL 9lest the stench has gone now)
also said that there must be a wopper of a fuel pump in the tank cause theres a lot of presure there..

havent had a chance to give it some yet but tomorow i shall.
ALSO WAS NOTED THAT AFTER PUTTING PLUGS IN CLEAN, THEY ARE COMPLETLY BLACK AFTER A FEW MINUITES DRIVING.

will be getting a haltech in the next month or so...

 

[sypher]

with regard to low compression on ALL 4 cylinders i would say its unlikelly to have been valve seating/timing problem as when checked was ok. it is my opinion that the problem you occured was the cylinder bores being ''washed'' this could happen for a number of reasons
1 (as said earlier) fuel pressure too high
2 flat battery causing slow turn over and will open injectors but poor ignition
3 for whatever reason spark int' failure

if the wrong coolant temp sensor was fitted to the engine there is every possibility that its manufactured resistance is different from the O E GTiR one causing ecu to think its coolant is eg -30'c so enriches mixture to compensate for fuel re condensing on manafold ports this could be the ROOT of your problem and what caused the bore ''wash'' hence low compression

Check fuel pressure and if its too high i would say tou either have a faulty reg' or a restriction in the return fuel line the pump can create upto 5-7 bar (depends on type) but its ''REGULATED'' by the regulator

if you already know this sorry but if you didn't hope it can help