Oh Hell No

[stocko]

hey guys, well story goes rb25det.... no power under 2500rpm and then creates boost but has no pull so i checked compression.

pulled all 6 plugs out held car under wot and tested results as follow

p1. 90 psi

p2. 90 psi

p3. 85 psi

p4. 80 psi

p5. 90 psi

p6. 95 psi

pulled timing cover off as thought belt may have jumped. timing is all good pulled tapet covers off to see if cam turns yes both do...

is it possible to be low on all 6 cylinders car starts and idles smooth!!!

help please?

[CEF11E]

sounds like belt slip to me. i have never seen all 6 equally low. are you sure the timing marks on the cam are in alignment with the crank?

[stocko]

yeah man they all line up perfect... i spoke to several repuatable tuners and mechanics and they still think it has timing issues! but it is lined up can the cam itself be out compared to the cam gear??

[Simon-S14]

no the cam cannot be, however other issues could be worn keyway in the crank, causing the crank to rotate a few degrees out of timing, ive seen this one a few times now.

was the comp test done with the motor warm, all plugs ut and throttle held at WOT while cranking?

[The Mafia]

what tester did you use?

I got one from supercheap and it read really low like this one.

Then I got another and it read 30psi too high.

You need a good quality one.

[mid life crisis]

does the compression change if you put a squirt of oil down each cylinder?

[stocko]

tester was an ABW brand and it was a screw in fitting one, car was tested cold, not sure about the oil

[Simon-S14]

should always test when motor is warm or close to operating temp for most accurate figures

[R31Nismoid]

its consistent, i say there is nothing wrong and the test wasnt done correctly

[Duncan]

yeah it kind of sounds like stuffed timing to me too if it is running OK but just no power.

possibly low compression can be caused by a really thick head gasket or aggressive cams with lots of overlap.

[Pal]

do what mid life said, do another dry run and then squeeze a bit of oil into each pot and test again see if the compression increases. if it increases alot then your rings are stuffed. little change, there ok

[Guilt-Toy]

YES the cam gear can move on the cam, if the dowl locator snapps on the cam then what happens is that the gears are still in time but the cam is retarded, this happened to my engine and it had 30psi in all cyls and it still ran as well.

Take the harmonic balancer off, take the timing covers off and put the engine on TDC and make sure the bottom timing mark is correct as well as the top ones.

Get a shifter and put on the cam (you need to take the cam covers off) and try turn the cam gently. If the cam turns without the cam gear turning then you would have snapped the dowl and it might only be a little bit out. It can get worse and if you dont fix it now it could slip around and smash valves.

Also check your compression tester, the engine could be all OK

[stocko]

could this snapped dowl sound like a tapping noise???