I have installed wideband o2 sensor and gage. My readings are lean most of the time with everything connected. I disconnected the air temp sensor and adjusted my fuel pressure to 36 psi. Now at cruse I'm about 12.5 to 1. But it still goes into about 14 to1 when at about 4000 rpms cruse speed. I need my MPS adjusted. The MPS hold vacuum.

Should I adjust it myself or send it to someone for calibration?

Well, start with this.
What year?
What ECU, mps, cht and Tps part numbers do you have?



You can add a resistor to the cht line, inline, to enriched your mixture, but after the car is warm it would not make enough difference.
You could also have an adjustment issue at your Tps that could be making this happen.

Stock parts, these cars run rich.
Though, IC you have a 76 and if you still have the cat and the stock air pump, you may see a lean mixture.

Also, air leaks can give you false readings if you exhaust is leaking.

36 psi is way to much fuel so once you find the actual issue, your car won't start, it will flood out.

Rich

36 psi will screw up the spray pattern, which should be a "fog", not a blast of fuel. Your HCs will go way up because the fuel isn't atomizing properly and isn't completely burning.

The Cap'n

I have tried several pressures and agree that 36 is too high. My problem is that at about 3700 rpms the air fuel mixture spikes above 14.5 to 1 and the motor has a dead spot. By increasing the pressure I have ir rich everywhere else.

The real problem is why is it so lean at 3700 - 3900 rpms? It is good above and below those rpms. And it doesn't matter if I'm full throttle or just trying to crusebthru 3700 rpms. Without raising the fuel pressure I have to pump the throttle to get it past 3700 rpms.

I have done these things since I have had this issue trying to resolve it.
Had the injectors cleaned and flow tested.
Cleaned and lubed dizzy
Tried 3 different trigger points.
Ohmed all ECU wires
Valve adjustment
And many other checks listed on here

Yes. You have the wideband to monitor any adjustments. Have you read Brads DJet write up on how to adjust? Just as Rich mentioned, check parts compatibility for your year model. *Note. MPS adjustments are very small. If the screw were a clock adjust one second at a time. IIRC. the inner screw will richen/lean the mixture across the board when turned by itself. Remember; very small adjustments.

I just went through this. It is not simple and helps to have a full understanding of the Bosch injection world of the 1970-s and 1960s. I just read an interesting article last night about the evolution of the system from the type 3 volkswagen to our type 4 systems.
I have no idea why you are running at 36 when the manual specifies I think 28 psi. I know that aircooled engines run cooler rich, but it is good to recall that stoichiometric is almost 15:1, so you have yet to report a truly lean value. I don't have the graph here, but how fast are you going when cruising at 4,000? Are you in top?

I have two thoughts. First, you haven't told us much about the engine, but if it is stock, I would run away from adjusting the mps unless there are signs that someone has already (un-) adjusted it already. They made them as best as can be for the engine and brain and they work great no matter what the gauges say.

Second, with all of that said, it may have a cracked diaphragm. I went in to start adjusting my MPS for a non-stock setup and bought a second MPS to rebuild. Reason? I wanted the stock MPS to fall back on. When I eventually took the stock MPS apart I found it was cracked even though it appeared to hold vacuum. Thanks to our racer Chris, these are available.

Good luck.

p.s. it helps to take notes along the way.

I tuned a MPS to my 2056 with a cam and porting and a 9:1 CR. I got the best results in 3rd gear and as Kent said make small adjustments. Very small. You should get the best preformance from 12.8:1 just coming on the throttel to13.8:1 at above 3500rpm and WOT.

Similar engine, similar results. The engine runs best a bit leaner than I expected. I suffered with it all summer long too, so adjust at your own peril.
Also there are 3 (three) adjustment screws. Although I spent most of my time with the little one.

Stock Djet 1976 minus air pump, EGR, Cat, and a few other unnessary pieces. I have added a resistor to the cht line. TSP is good and adjusted.

This has been a long almost 1 year process for me and this car which I bought last October. Started with running rough (dirty injectors, bad adjustments (valves, TPS). High oil temps (still working but last night I found that the timing mark is ~7-8 deg off, more on that later) installed 02 wideband and I'm running lean (may be tied to the timing, I may have a reselution when I go home and retime using new make).

I don't think that is an iss with spray, as during the flow testing they test at 40PSI and it had good spray patern.

That may be, but it isn't what known experts say. There is a pretty solid consensus that you are at or beyond the limit. Another problem that the Capn didn't mention is retention of fuel when the pulse isn't happening. The springs are finite in holding the pintle and you can get a dribble if you go high enough in pressure.

Curious about what led you in that direction. I brought my car west from Baltimore at full on fuel pump pressure cause unbeknownst to me the regulator was stuck shut. Ran terrible, really really bad. So I went the other direction of course.

[/quote]
Stock Djet 1976 minus air pump, EGR, Cat, and a few other unnessary pieces. I have added a resistor to the cht line. TSP is good and adjusted.

This has been a long almost 1 year process for me and this car which I bought last October. Started with running rough (dirty injectors, bad adjustments (valves, TPS). High oil temps (still working but last night I found that the timing mark is ~7-8 deg off, more on that later) installed 02 wideband and I'm running lean (may be tied to the timing, I may have a reselution when I go home and retime using new make).
[/quote]

I have the same car. You can ditch the resistor. It should run great with the stock fuel injection if everything is in working order. Mine is white faux bumblebee sprayed by the PO over silver. High oil temps seem common.

I agree that 36psi is way to high but allows me to keep from running way to lean.
I may have found the root cause last night. I checked the TDC mark on the fan compared to the TDC mark on the flywheel. I found that it was ~8 deg off, like it was about where the 7.5 degree mark would be on the 1.7. I have made a new mark on the fan at TDC which matches the flywheel mark.

I will test this tonight, I expect this will help with the high oil temp and possibly the lean condition. I want to go back to the correct fuel pressure.

Sounds like someone painted in the normal mark for timing a 1.8 at idle (8 degrees). A 1.7 would have a mark at 5 degrees. For a 2.0 you time using the 27 degree BTDC mark. The top dead center mark is normally not used for timing at all, but is instead used for valve adjustment. If you have an adjustable timing light you can probably use TDC as a base, but look for the mark at 27° while you are at it.
Can you say what the A/F ratio that you are looking for is? You say lean, but the numbers you give seem actually to be technically rich, i.e. below 14.7 . It would help to know what you are trying to get.

to much advance...yup that would do it.

Now you will have to go back and re adjust everything else you changed to get it to idle properly.
This is when it will flood right out of the gate.

rich