Gad! Reminds me of my own situation when I purchased a car that someone had "Big Bored." Took my four years...four years to get it running. Now it runs like a top. I think I bothered most of the gentlemen who previously responded to you and appreciated all their advice. But there is no magic bullet. So here goes my story.

I had all the symptoms you describe, plus hot running and a horrible dip below idle everytime I left off the accelerator. First thing I did, after ignition, wires, checking all the sensors, checking the MAP for vacuum, etc, was found an old 140 (B20F) ECU for $10 and swapped it out to see if the ECU was bad.(after unsuccesfully substituting a $300+ factory reconditioned B20E ECU). That cured the idle dip. Makes sense..with the bigger bores, compression ratio should decrease, so an ECU suited to lower compression should work better.

Then I started to play with the fuel pressure, gradually increasing it to 32 PSI, to handle the top end stumble.Then I constrained the centrifugal advance and advanced the timing to 18 degrees BTDC. All that took about three years...all the while it ran OK, but not like my previous stock 72.Ran rich.Had to use hotter plugs. Then it really started to miss. A leak down test said there was a leaky intake valve. I was about ready to have the head pulled and a valve job done when a crusty old used car guy recommended some stuff to clean the carbon out of the top end. Can't remember what it's called, but I got it at the local Ford dealer for $20. The situation improved but I still had a miss. Took it to a competent vintage Volvo mechanic and by the time they got it the miss was barely there. They checked compression (175 X 4) and said it might be an ignition problem. By the time I got it back that elf oil must have fully worked it's magic because the miss was gone and I couldn't make it run badly..in fact was able to decrease the fuel pressure and switch from premium to middle grade without knocks. Man, the thing purrs, even idles well. I'm convinced it was a carbon and valve sealing problem all this time.

So, to summarize my particular formula: Restrict top end of centrifugal advance slightly. Pertronix ignition. Timing at 18 degrees. B20F MC (you may have to do a work around on the cold start circuit..I use a momentary contact button under the dash). Fuel pressure at 31 PSI. NGK BP5ES (or whatever they are) plugs...5, not the normal 6. One step hotter. And a can full of that good old professional grade top end decarbonizer once a year.

I hope this contribution will add to the volumes of bad advice available on the web. Like you said, there are really too many variables when you start big boring these things.For me it was valves. For you, it's your own struggle. Hang in there...But don't wish too hard. Now that mine runs so well I don't even know that I'm driving it and much of the thrill has gone.

Super glad to hear you got a step in the right direction. Before you buy a MAP check these out. I got these from a link that was put out on the 1800 list a while ago. They are accurate for the cars I've seen in driveways and pick and pulls.

0 280 100 010
1970 1800E (4 speed)

0 280 100 015
1971 1800E

0 280 100 035
All injected 1972 Volvo 140 models (with B20F engine)
All 1972, 1973, and 1974 Volvo 164 models (with B30F engine)
All 1972 Volvo 1800E and 1800ES models (B20F engine 4 Speed and Auto)
(Compression lowered to 8.5 to 1)

0 280 100 053
1973 and 1974 164 is (with automatic transmission)

0 280 100 054
1973 140 series and 1800ES (B20F 4 Speed and Auto)

0 280 100 059
1975 164 is (with automatic transmission)

0 280 100 066
1975 164 is (manual trans)
--
Dave Shannon
Spring Valley, California
'67 1800s
'73 1800ES
'88-240
my pages

I played hooky this afternoon, and played around...I think I am down to it being a bad MAP sensor, I'm going to check with a buddy that might have a spare.

First, I went through the whole list on vclassics.com archives, all checked out.

All plugs are very black, but not wet maybe 20 minutes time since new and they are already this black. Compression, cam lobes, etc are fine. Checked the temp and pressure sensors from the ECU plug, no problems noted. Injector resitance was just under 3 ohms each. Trigger points test fine, as did the throttle switch. Fuel pressure did not climb, negating a possible partly clogged return.

Ignition checks fine, This has the Crane unit in it, I reset the optivcal trigger ( it was pretty close) no change. Stock computer makes no improvement.

The one thing I noticed and failed to mention earlier, is that it runs fine for 30 seconds or so when first started, then goes rough and rich, and will do that each time. It won't accelerate well now ( I may have messed up the throttle switch adjustment) but once up to 2000, smooths out a bit, then goes rough and rich again.

There's not much left but try a different MAP is there?

I had similar problems sometime back and was trading between several computers
and several MAP sensors. It turned out that the ones I was using were BOTH
bad - so when I was trading different MAPsensors I had a bad computer in and
when I was trading different computers I was using the bad MAPsensor.

I could perhaps loan you a verified MAPSensor to assist in your effort if you'll
return it to me when you're through. Normally you can get one on ebay but
till you check it out you can't be SURE that it's good. Prices usually run
about $30 or so. Resistance checks prove the wires aren't broken or shorted
but do NOT prove functionality.

E-mail me offline.
--
George Downs Bartlesville, Heart of the USA!

The poor idle quality indicates something for sure - of course you know that. So the big bore kit, the compression, are not part of the problem at all. The cam is known to work with the D-jet, and so that is also not a problem.
The trigger contacts may very well be the problem. Set the idle speed to make it run, and disconnect the injectors to find any that aren't contributing. You can also check the ignition wires, and doing so would be a good idea.
The MAP sensor you mention was checked for leaks. Check again and be sure there are none at all. If you have a spare, plug it in.
Wires can drop off those old Bosch connecters, and it can be as simple as that.
I am surprised that you mention the reostat makes a noticeable difference. On an engine running well the change can be very minor, so on one running that poorly I can't imagine how you could tell. Set it full lean in any event while looking for the trouble - CCW as I recall.
They don't call it Demonic Tronic for nothing!

As the folks over on the 1800 list said, D-jet hates modifications. Even the ipd computer won't make up for it, the limited tuning just won't handle all the variables you have. Get carbs or megasquirt . While you're at it search the archives for some of Phil S' comments on motor building, it's an art.

You also might want to read his article at
http://www.vclassics.com/mppe1.html

I'm not trying to bumm you out, just let you know that what the PO did may not be the best combination of parts, it sounds a lot like Phil's first motor in the article. You probably will be able to get it running well, but I'd be surprised if the stock injection will do it.
Good luck, the ES' are well worth the effort and you will be happy when you are done.
Cheers
--
Dave Shannon
Spring Valley, California
'67 1800s
'73 1800ES
'88-240
my pages