Engine seems to rev fine at idle, but under load it bogs and won’t go over about 3k rpm under load, even small hill climb. Compression test showed 170 psi on all six. Fuel pressure is solid @ 70 psi at idle rev and load. Checked timing belt and tensioner, all perfect. Checked vvt solenoid and screen @ oil filter mount, all good, solenoid is Mechanically actuating and blow test proved on and off. NO CODES from OBD2 scanner, no check engine light. These symptoms were why it was parked 2 years ago. New gas was added to nearly an empty tank before all the above testing.
The reason I went towards timing jump was the engine load power problems and I heard some “valve interference” noise at no load quick rev’s at the higher end, maybe around 5K.
The reason I looked at the VVT or VTEC was there were a lot of posts about it’s possible issues, especially what was now easy to check, but this part of it tested good, visually, mechanically and electrically. Yes, I thought about clogged cats. I think there are three, one on each bank and a aft for all six, but either should throw a code. To meet emissions, monitoring this is a requirement.

so, I’m stumped. I now believe the Engine control module is going into limp mode, but that (among everything I can think of) should throw a code.

 

Yeah, if it is in limp mode then would think the CEL would come on and store a DTC.
It could be clogged exhaust cats. Check short and long term fuel trims.
Try taking the upper O2 sensors off and take her for a spin.
Or, it could be timing.

 

I would think clogged cat would throw a code, but was one thing I was thinking of. The timing looked dead on, but I replaced the belt and tensioner, because they were due and now easy to get to.
I checked fuel pressure at the throttle body, loaded and unloaded and it was rock steady at 70 PSI.
What are fuel trims?

 

A clogged cat won't necessarily throw a code.
There are adjustment made by the ECM to the air/fuel mixture to maintain a balance.
These adjustments are called fuel trim.
Fuel trim is tool displayed as a percentage on a scan tool.
If the fuel trim is negative then engine is running rich which can cause the cat to burn out and block the exhaust.

Just want to know how you checked the ignition timing.
If too little spark advance then there will be low power
And the rpm could be limited.

When key is first turned to the on position, do you see all the dash lights (ie check engine light, ABS, alterntor, etc.)??

 

I did not check ignition timing or fuel trim. I will look at this when back together, hopefully this weekend. I assume I can do all this with my scan tool.

thanks for the info

 

Since the last post car jumped timing, bent valves so I did a top and rebuild . Machine shop replaced most of the valves I got it back together, next I got crankshaft position sensor and knock sensor error code. I replaced both sensors checed the wiring continuity in the harness put it back together and I’m still getting these error codes. The car still has no power as before. I HATE this car.

 

Okay, rebuilt head, and timing spot on, ....
Have you tried removing the up stream O2 sensor and see if it runs better??

 

I’ll try that this weekend and look at fuel trim. Does any of this affect knock sensor?

 

BTW using Autel MaxPro OBD2 scanner.

 

Check out fuel trims explained on youtube.
It can help diagnose problems through fuel trims