Cold Start Issue 914-4, Admitting I'm stuck and asking for help Options

[Blue Lightning]

Make sure you’re using the proper thermocouple type. Likely k-type but I’m not familiar with that gauge. Idle time and an 8 mile drive without heavy load like hills and WOT, isn’t going to get heads terribly hot if all is working well and the engine is properly tuned.

However it is odd that your head temps would be low and the oil temp would be so high that quickly. Oil temps usually lag head temps by 5-10 minutes since there is the whole thermal mass of the oil and the case that need to be heated. Did you inspect the top of the oil cooler yet?

Yes, if backfiring is getting worse as it warms revisit valves.

There should only be the most minimal of perceived drag on the feeler gauge when doing the adjustment. If you’re not very careful the adjustment changes when tightening the jam nut and sometimes you need to sort of adjust a smidge loose to anticipate the change that occurs when the nut is tightened. Verify again when tightened.

Thermocouples are J-type, and are the ones that are sold with the CHT. It definitely was a low-effort drive (top speed ~55).

Too many house chores piled up the last few weeks that I needed to address this weekend, so I have not had time to inspect the oil cooler yet. It was a pain to get the thermostat wire set correctly, so I wanted to do it while the flaps were open (i.e., engine warm). Is there a way to remove the top engine tins without disconnecting the thermostat?

I ordered a set of bent feelers (https://www.amazon.com/dp/B0CGRZKT71) which I'm hoping will help with the valve adjustment. Will watch more closely on the drag. I'm beginning to see why most modern cars have hydraulic lifters!

[Blue Lightning]

I posted picture of the flaps for 3/4 side but I don’t see that it has ever been confirmed — does your engine have the flaps in place?

The externally-visible flap mechanism components (bar, return spring) are in place. I have not removed the tins to confirm, but have no reason to believe they are not. When I got the car, the thermostat was broken, which I believe means the flaps (if present) were in the "hot"/open position.

[emerygt350]

Just as a data point (everyone's cars are different)I don't think my car has hit 220 oil temp yet this spring and I have put almost 800 miles on it, extensive interstate miles at 75 in fifth gear with the heads (cylinder 3) at 370 in a very hilly area. It is colder up here of course but that is even at 70 degrees. The timing and valve issues could put more heat in the oil versus the heads but I really can't see having heads barely cracking 200 when the oil is 220. I am at 200 cht in a 1 mile drive to work in the morning on a freezing day.

If the flaps are working and nothing has made a home in there, I really suspect the gauges are not working properly. A quick way on the 73 to check the flap action is to use the coil mounting holes and a hangar or just a long screw driver. You could also use the oil sender hole or the spark wire holder near there to get an endoscope in there to look at the cooler. You may be able to use the oil pressure sender hole in the tin to look with an endoscope at the cooler.

Where exactly are your cht senders mounted?

[Superhawk996]

I posted picture of the flaps for 3/4 side but I don’t see that it has ever been confirmed — does your engine have the flaps in place?

The externally-visible flap mechanism components (bar, return spring) are in place. I have not removed the tins to confirm, but have no reason to believe they are not. When I got the car, the thermostat was broken, which I believe means the flaps (if present) were in the "hot"/open position.

Along the lines of verifying assumptions I’d verify with a borescope or inspection mirror that the 3/4 flap is present and that the top of the oil cooler isn’t clogged.

Agree it is unlikely a 3/4 flap is completely missing but it would cause oil to run hotter and head to delay warm up.

[Blue Lightning]

Just as a data point (everyone's cars are different)I don't think my car has hit 220 oil temp yet this spring and I have put almost 800 miles on it, extensive interstate miles at 75 in fifth gear with the heads (cylinder 3) at 370 in a very hilly area. It is colder up here of course but that is even at 70 degrees. The timing and valve issues could put more heat in the oil versus the heads but I really can't see having heads barely cracking 200 when the oil is 220. I am at 200 cht in a 1 mile drive to work in the morning on a freezing day.

If the flaps are working and nothing has made a home in there, I really suspect the gauges are not working properly. A quick way on the 73 to check the flap action is to use the coil mounting holes and a hangar or just a long screw driver. You could also use the oil sender hole or the spark wire holder near there to get an endoscope in there to look at the cooler. You may be able to use the oil pressure sender hole in the tin to look with an endoscope at the cooler.

Where exactly are your cht senders mounted?

CHTs are the ring-type that fit on the spark plugs (replaced the thin washer on the plugs with them).

Thanks for the good ideas on how to get to the 3/4 flap. I was planning on going in through the fan shround, but that might be easier!

[emerygt350]

Just as a data point (everyone's cars are different)I don't think my car has hit 220 oil temp yet this spring and I have put almost 800 miles on it, extensive interstate miles at 75 in fifth gear with the heads (cylinder 3) at 370 in a very hilly area. It is colder up here of course but that is even at 70 degrees. The timing and valve issues could put more heat in the oil versus the heads but I really can't see having heads barely cracking 200 when the oil is 220. I am at 200 cht in a 1 mile drive to work in the morning on a freezing day.

If the flaps are working and nothing has made a home in there, I really suspect the gauges are not working properly. A quick way on the 73 to check the flap action is to use the coil mounting holes and a hangar or just a long screw driver. You could also use the oil sender hole or the spark wire holder near there to get an endoscope in there to look at the cooler. You may be able to use the oil pressure sender hole in the tin to look with an endoscope at the cooler.

Where exactly are your cht senders mounted?

CHTs are the ring-type that fit on the spark plugs (replaced the thin washer on the plugs with them).

Thanks for the good ideas on how to get to the 3/4 flap. I was planning on going in through the fan shround, but that might be easier!

I had some luck peeking in there that way.

I have found that if the thermocouple ring is not seated well you get much lower readings that you should. If it is a little crooked it is easy to think the plug is seated when it is not. Is one on Cylinder 3? That is the hot one where the vast majority of valves seats go a wandering.

[Blue Lightning]

I had some luck peeking in there that way.

I have found that if the thermocouple ring is not seated well you get much lower readings that you should. If it is a little crooked it is easy to thing the plug is seated when it is not. Is one on Cylinder 3? That is the hot one where the vast majority of valves seats go a wandering.

I put them on the two that were easy to reach, #2 and #4. Maybe better to move...

[Blue Lightning]

Quick update. Readjusted (loosened up a bit) the valves Saturday and took the car for a drive. It was a short drive as I had one of the air inject tubes back itself out and get lost along the side of the road. Took me a while to figure out where the leak was. Need to run by Home Depot and find a bolt to use to plug that hole. (IMG:style_emoticons/default/shades.gif)

[Blue Lightning]

Took car out for a longer drive today, about 40 minutes. Car started fine, restarted fine. Idle is excellent (IMG:style_emoticons/default/aktion035.gif)

I'm getting hesitation at throttle tip-in (part to wide open throttle is fine), and still getting some backfires especially at low (1000-2000) rpms with the throttle only opened a bit.

Backfires I typically think of as timing problems, but can also be running lean?

Thoughts?

[Superhawk996]

Lots of pages here but a quick look at page 1 I don’t see any confirmation that TPS is adjusted and that you have confirmed the traces that “pulse” and signal the ECU to inject more fuel - aka - accelerator pump enrichment as throttle tips in.

Backfires can be related to:
Ignition as you stated
Lean mixture (or transient lean as related to TPS above)
Mis adjusted valves
Poorly sealed exhaust especially at the heads

[Blue Lightning]

Lots of pages here but a quick look at page 1 I don’t see any confirmation that TPS is adjusted and that you have confirmed the traces that “pulse” and signal the ECU to inject more fuel - aka - accelerator pump enrichment as throttle tips in.

Backfires can be related to:
Ignition as you stated
Lean mixture (or transient lean as related to TPS above)
Mis adjusted valves
Poorly sealed exhaust especially at the heads

Thanks. I've checked the TPS for idle adjustment and for the "10 pulse" several times and it always comes up correct.

Am going to try to take it for a drive and check the mixture next, but the only mixture adjustment I am aware of is the idle one on the ECU, which shouldn't be the problem here. I guess the fuel pressure is an indirect mixture control, too, but I would think this would cause problems across the RPM range...

[emerygt350]

The ECU is only for idle (although I wonder sometimes), however, you can use the fuel pressure to troubleshoot your backfire. Bring it up to 31 and see if the behavior changes.

[Ron914]

[b]

Thanks, but I think that second one is the fuel pressure regulator?

@Blue Lightening
I am sorry You Are correct that is my Fuel pressure regulator ,In some ways they look the same and I picked the wrong photo to post .
I was just wondering how your getting along with the D-Jet ? I am still working on my car . I have had my Throttle Body rebuilt and I am getting ready to open my MPS and replace the diaphragm . I had to purchase some additional gauges (AFR,Vacuum,and CHT ) so that once the diaphragm is replaced I can tune my MPS for my 2056 .I have had most of the issues you have been posting . Just curious where you are at now .
Thanks

[Blue Lightning]

Following up on this thread. I finally took the car into AutoAtlanta, and they figured out that cylinder 1 has a 55% leak down. So looking at at least a top-half engine rebuild.

Thanks for all the suggestions/comments!

[Superhawk996]

Well that just sucks! Sorry to hear that but at least it aligns with the inability to make strong vacuum and the continued backfires.

Thanks for posting the follow up!

Hopefully you’ll be back on the road sooner than later!

[emerygt350]

Nothing to fear with a top end rebuild. Glad to hear you found the culprit.

[Blue Lightning]

Thoughts on shops to do engine building?

On one end of the spectrum, Raby's Aircooled is up the road from me. But $$$$$.
On the other end of the spectrum, a place like SCAT, but various reviews of questionable quality of work.
AA said they can do a top-end rebuild. Another customer recently had one done in the $15k range (including removing and reinstalling engine, tuning).
AA also has a full rebuild (https://www.ebay.com/itm/264614882718). Have not gotten from them what the difference between this and the top-end rebuild is, or the price difference.
I came across PMB which seems to do quality work (https://pmbperformance.com/products/pmb-2000-2056-type-iv-engine-restoration-for-porsche-914-1970-76).

There are a handful of local shops as well:
https://grahameverettmotorsport.com/
https://www.yelp.com/biz/auto-europe-atlanta
https://www.goldcrestmotors.com/engine-gearbox

[T.Rick6]

If I were in your shoes I would do a top end rebuild myself; you have the mechanical aptitude and it's really not that hard.

Give Al Meredith a call or PM, He's in ATL as well; depending on his schedule he may be able to help. VERY Reasonable and he knows what he's doing.

If money is not an issue I would get PMB's 2.3, fabulous motor

Just me but I would not take it to AA, too much $$$$

(IMG:style_emoticons/default/beerchug.gif) Todd

[emerygt350]

I did mine for under 1500. New seats, seals, valves, pistons, sleeves. It is really easy and I took my time and enjoyed it.