High fuel pressure concern

[The_big_dill]

Hi all,

Recently rebuilt an engine that had a burnt valve.

Engine starts great, but:

- Issues idling
- Lean AFR
- Fuel pressure too high (over 10K PSI)

During rebuild:

- Injectors cleaned (filters replaced)
- Used Autotech HPFP internals installed
- CS Injector seals with all new OEM upper seals

My searching has led me to issues with low pressure, but haven't found anyone with this problem.

I uploaded a log.

There may be more than 1 issue at play here. The O2 sensor grounds that were bolted to brackets have not been secured because all those brackets rusted away.

On a side note, engine sounds like a diesel once its warm. I thought it was the HPFP, but it doesn't sound right:

https://www.youtube.com/watch?v=h14Xu2gsw24

Disclaimer: I have never been in a properly running speed3, so I have no reference.

[Fstrnyou]

Even if the ECU got 0 volts form the rail pressure sensor, the highest pressure possible is about 2199psi or something like that.

I'm not sure if the ECU would recognise or interpret a negative voltage to read higher pressures.

[Vansquish]

Originally Posted by The_big_dill Hi all, Recently rebuilt an engine that had a burnt valve. Engine starts great, but: - Issues idling - Lean AFR - Fuel pressure too high (over 10K PSI) During rebuild: - Injectors cleaned (filters replaced) - Used Autotech HPFP internals installed - CS Injector seals with all new OEM upper seals My searching has led me to issues with low pressure, but haven't found anyone with this problem. I uploaded a log. There may be more than 1 issue at play here. The O2 sensor grounds that were bolted to brackets have not been secured because all those brackets rusted away. On a side note, engine sounds like a diesel once its warm. I thought it was the HPFP, but it doesn't sound right: https://www.youtube.com/watch?v=h14Xu2gsw24 Disclaimer: I have never been in a properly running speed3, so I have no reference.

Originally Posted by Fstrnyou Even if the ECU got 0 volts form the rail pressure sensor, the highest pressure possible is about 2199psi or something like that. I'm not sure if the ECU would recognise or interpret a negative voltage to read higher pressures.

So...you both need to read more carefully. The OP's AP is reading in kPa, not in PSI. 13,000kPa of fuel pressure is 1885psi, which is fine for that vehicle. You can change the scale to PSI in the AP's settings menu, if memory serves.

The lean AFRs are interesting, because the ECU appears to be trying to pull additional fuel (make the mixture even leaner) despite already being very lean at idle. To me, that suggests that you've got one or more of the following:

- a bad MAF calibration (more generally, a bad tune, or a tune that isn't appropriate for your modifications - in particular the ID of the MAF housing)

- a failing or incorrect MAF sensor (seems unlikely, as the car is running and seems to be reading reasonable numbers)

- one or more bad O2 sensors (seems unlikely, as the AFR numbers and fuel trims aren't pegged at specific values)

The rattling doesn't sound good though. It sounds way too loud to be injectors, and it appears to be coming from all four cylinders rather than just the driver's side or just the passenger's side of the motor. If it was the former, I would suspect the HPFP and/or a failing HPRV, and if it was only the latter, I would suspect the timing chain.

[Fstrnyou]

My reading is top notch. He said PSI so I responded in kind. My claims that 2199PSI is about the max the ECU can interpret is, for the sake of arguement, correct.

[Vansquish]

Originally Posted by Fstrnyou My reading is top notch. He said PSI so I responded in kind. My claims that 2199PSI is about the max the ECU can interpret is, for the sake of arguement, correct.

That may be, but the OP's video clearly shows kPa. Operating under the presumption that you had watched the video, there was only one conclusion to make: neither you nor he had recognized the units being used.

[Fstrnyou]

Perhaps my reading is bad then. I thought he posted a datalog, which I am not able to open on my phone, so I didn't click it.

You win.

[The_big_dill]

No need for a flame war haha.

I appreciate both of your inputs, admire the attention to detail, and learned something new. And to pay attention better.

I am glad it's all good with the fuel pressure.

Regarding the timing, I have been doing some thinking and reading and I'm pretty positive I messed up one step in timing the engine.

All timing components are new and OEM, but I believe I tightened the cam sprockets before I released the tensioner. Sound like a possible cause to this?

Next steps, I would like to retime without removing the timing cover.
- could I loosen the exhaust sprocket, reapply the chain tensioner and retighten, or do I have to do this on the intake side?
- If I loosen the cam bolt, I must replace the friction washer, correct? If so, can I remove the sprocket without removing the timing cover?

The only other thing is that the crank position sensor was installed without any marking or positioning. Do you think my symptoms could be a cause of the ckp position?

Thanks again!!

[Vansquish]

There's no flaming going on here at all, and if there are any hurt feelings, I don't think any of us intended that to be the outcome.

In any case, if you do retime the motor, you definitely need new friction washers, as they are single-use items which will fail if you try to reuse them.

Having not messed with the physical timing components on my car, I don't know if your tensioner-theory makes sense. I'll happily defer to someone with more knowledge than I have.

In any case, what is the internal diameter of your MAF housing? Does the MAF housing have an air-straightener? What tune are you running?

[Fstrnyou]

What are these friction washers you speak of? Lol
Call me crazy, but I never have to worry about that garbage ever again with pinned cams.

[The_big_dill]

Originally Posted by Vansquish There's no flaming going on here at all, and if there are any hurt feelings, I don't think any of us intended that to be the outcome. In any case, if you do retime the motor, you definitely need new friction washers, as they are single-use items which will fail if you try to reuse them. Having not messed with the physical timing components on my car, I don't know if your tensioner-theory makes sense. I'll happily defer to someone with more knowledge than I have. In any case, what is the internal diameter of your MAF housing? Does the MAF housing have an air-straightener? What tune are you running?

Thanks for the quick reply.

I did read that lean running could be a result of MAF calibration being required. It is the Cobb intake, from filter to the turbo. ( I believe it's called TIH and SF). I am running the Cobb stage 1 tune, iirc.

Should the tune have the maf calibration already set?

[Vansquish]

Originally Posted by The_big_dill Thanks for the quick reply. I did read that lean running could be a result of MAF calibration being required. It is the Cobb intake, from filter to the turbo. ( I believe it's called TIH and SF). I am running the Cobb stage 1 tune, iirc. Should the tune have the maf calibration already set?

You should definitely be running a map with the MAF calibration for that particular intake. I believe that COBB offers an off-the-shelf (OTS) map that includes the SF and TIH/TIP as part of the calibration. That said, you really should regard the COBB OTS maps as a stopgap measure and nothing more. They are really pretty piss-poor calibrations for this platform.

https://www.cobbtuning.com/maps/2007...stage-1-sf-map

Edit:

Please note that if you have an aftermarket downpipe, you need to be running a map that accounts for that fact as well.

https://www.cobbtuning.com/maps/2007...dm-stage-2-map

[Jeff23spl]

Usually the last step after a timing job is to give it few turns in the right direction (clockwise in this case) and re check if everything is still ok....This let the tensioner set properly and let you see if the play was taken on the right side.

you can still check this prior to loosen any bolts. Just put back the crank pin to set TDC when the first cams lobes are facing and check if the cams are timed ok with the rear end flat surface aligned horizontally....(As explained in the ''how to vvt'' )

I don't think you could replace a washer or bolt without removing the cover to release the tensioner.
Trying to just loosen it and tight it back at the correct place is a risk that could bend valves if oil drop on the old washer and it slip later...

[The_big_dill]

Thanks for all the great replies, this community is awesome!

I tore into it this evening and found the recirc valve hose was no longer attached to the TIP... nice and hidden under the intake. I attached it and the car runs so much better, I still need to check AFRs.

As for the knocking/ticking coming from the valve cover, it only happens when the engine is warm... When the engine is cold, the engine runs smooth and sounds right. The warmer it gets the worse the sound is.

Is this Valve lash or a defective VVT? I will re-check valve lash, but I am not sure how long the VVT has been sitting on the dealers shelf, will also check part number of the VVT when I check lash.

[Jeff23spl]

nice find ! this is something the usual boost leak test would have showed very quick.

You can still look at your timing for peace of mind....but a new vvt should be fine, it needs to wear out first before going bad even if you didn't get the updated unit (And i would be surprised if Mazda had stocks of the original bad units on shelf for sale...)

[The_big_dill]

Originally Posted by Jeff23spl nice find ! this is something the usual boost leak test would have showed very quick. You can still look at your timing for peace of mind....but a new vvt should be fine, it needs to wear out first before going bad even if you didn't get the updated unit (And i would be surprised if Mazda had stocks of the original bad units on shelf for sale...)

I do not know if it is anything to do with the timing really, as the sound sounds like its coming from the center of the valve cover, not the timing chain tunnel or the timing cover. But that is the only thing I believe I made a mistake assembling.

I started a new thread for the chain problem as it seems like this is the wrong forum section for this discussion.