230K B230FT

This car has been running great after a headgasket replacement that included freshing up the head. It had a clean up cut and I lapped the valves about 4000 miles ago. The check engine light has been coming on indicating lean/rich conditions. It was off for a good period after replacing the o2 sensor only to come on again and then go off when I cleaned the throttle body... only to come on again several hundred miles later. So it has been on for a few thousand miles.

Round trip of 700 miles. Checked mileage on first leg and was pleased to see it was 26+. The only complaint I have had since the headgasket work has been the check engine light and a "loping" idle. The idle control motor seemed to be working properly. Cleaning the throttle body did not solve the problem.

On the return leg the car stalled several times after an initial startup when I put it in gear. Otherwise things seemed to be normal. When we got about five miles from home the car died as I tried to pull away from a traffic light. It started right up but then stalled a short time later. This stalling problem persisted. It died at speed several times but caught again as it was coasting down. I noticed that the tach still registered as the engine lost power.

The last several miles were touch and go with stalling but with a quick startup only to stall again upon any effort to accelerate. I was able to get back to our residence and coasted into the garage.

Next morning I swapped out the fuel injection relay and expected it to be fine, but it was not. Now the symptoms were a quick start up but as I tried to rev the engine it would backfire through the intake. I did a quick check of the fuel pressure and it was spot on and the fuel pressure regulator responded correctly when I pulled the vacuum hose. I had convinced myself that the problem was fuel related but things seemed to be checking out.

With the check engine light on all the time I was not alerted to other things that might cause it to go on so I pulled the codes. The lean/rich codes were there, but there was also one that pointed to the AMM. I had a spare in the travel box in the trunk so I put it in place and that solved the problem.

I don't know when the AMM would have caused the check engine light to go on but perhaps it would have gone on when it started stalling on startup on the return trip. After replacing the AMM I had the opportunity to fill up the fuel tank and when I checked the mileage for the return segment of the trip I found it had dropped to 21 miles per gallon.

After replacing the AMM I no longer have a loping idle.

Randy

Thanks for the excellent description of your problem and the evolution of solving it.

The AMM-MAF sure is one mysterious black box. One of the few parts that switching out is the best solution (once the problem points to it!).
--
I own a Volvo or Does Volvo Own Me? Try the easy to search Expanded Style FAQ Index http://40mph.com/Brickboard_700-900_FAQ_Expanded_Index_Version/

"So it has been on for a few thousand miles."
All because there were no adhesive ducks in the bathtub.

Sorry for the 99% likelihood that flew right past you. I just had to find this amazing coincidence between your post and a re-run episode of Big Bang Theory I saw last night.

Sheldon's analysis aside, I was impressed your limp home mileage was 21. I "limped home" recently from a 3000 mile road trip at 18 mpg, costing us about $100 extra in fuel. Not an AMM, but the screw mounting the AAV had backed out on our 79 244, leaving both it and the CPR without an electrical ground. Something I could have fixed on the road if I had been sharp enough. Sadly, no check engine light, just frequenter fillups. 21 mpg would have been nice.

Nice catch having a spare AMM to prove it.

--
Art Benstein near Baltimore

A boiled egg in the morning is hard to beat.

So am I lucky to have a Regina ignition system or does it have it's own set of problems? If so, I haven't come across them yet in 11 years. I do carry a spare air temp sensor (airtex $5.99 @ rock auto), I've been thinking of also picking up the manifold pressure sensor which as I understand it is the other component in determining intake air mass.... but I have never ever read on this board about one failing.

Total sidebar... on my 240 I re-apply thermal paste to the power stage every couple of years. I've read that the Regina has an internal power amplifier in the coil pack. Can this, does this need to be serviced with thermal paste?

Thanks for this post: (I had this problem and I fixed it, here's what i did)

Matt

--
'90 245 290k, '93 945 296k

Dear matt82dl,

Hope you're well. The only "service" work needed for the Regina coil/power amplifier is to keep clean the contacts, that join the coil and the power amplifier.

Over time, these contacts - as do all non-sealed electrical contacts - corrode. Sometimes the corroson is heavy/obvious. Othertimes it is think/almost invisible.

These contacts can be cleaned with very fine steel wool or very fine sandpaper. I then apply a thin coat of di-electric grease, to the contacts. The contacts push aside the grease, which then seals the contact point against moisture. That seal should inhibit corrosion.

Hope this helps.

Yours faithfully,

Spook

"I've read that the Regina has an internal power amplifier in the coil pack. Can this, does this need to be serviced with thermal paste?"

No thermal paste needed. The electronics are embedded in that finned aluminum mass that supports the coil. You can see it on the underside by removing the 2 bolts holding it to the inner fender.

That said, I did replace mine a couple of years ago when I was getting a suspected intermittent loss of spark. The FI continued to work, sending enough unburnt gas to the cat to make it glow red hot.

Coil and amplifier are sold a single unit (1367438). Mine came from Tasca for $114.57 delivered.

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.