In my case the CPS just died, in the driveway fortunately. But I have had electronic ignition gear get flakey when hot, including running rough and low power. The CPS should be a go no go kind a of thing, but the CPS is cheap enough to change out to eliminate.

The Camshaft sensor will throw it's single code and light the check engine light even if a little loose or it has a dirty connector, and yes a bunch of stuff has to come off to change it.

 

After reading your opening symptoms on this thread, I can't help but think about MAYBE looking at a restricted exhaust system??? loss of power, engine not revving up correctly etc..just a thought.

 

How would the exhaust get blocked? Clogged Cats?

 

@austinlandroverbill clog cats are the mostly likely cause of restricted flow. You can check the cat temp with a infrared thermometer, to see if teh are running hot. A seriously dent muffler or exhaust pipe can do it too, but that is usually obvious when you look at it.

 

Thanks for the reply. Could they suddenly catastrophically clog as it was running with occasional loss of power issues before it completely died.

Problem now is how to get them hot. Won't run for more than 2-3 seconds: starts, revs up to 2,500rpm or so, drops to under 500rpm, then burps a couple of times (really weak backfires) then dies.

Started a new post as I've replaced the CPS -- fifteen minutes to disconnect old CPS and install new one at the bell housing, then took three 1-2 hour attempts to get that connector off, ugh, what a PITA, the Brit that made that harness connection so short and non-intuitive (e.g., the sensor end connector is secured in the bracket rather than the harness end connector) should be forced to replace a couple himself to see the error of his ways by sacrificing his own skin and blood to the car gods.

I've got new coil packs, will replace those today (easy peasy job since I relocated the packs to the front of the engine compartment).

If the coil packs don't fix it (they have 190K miles on them as well, so good time to do a pre-emptive servicing anyhow), I am going to spray some starter fluid in to confirm I don't have a fuel delivery issue. Any thoughts about where I should spray it in?

 

@austinlandroverbill well it is not recommended to run long but you can crack the bolts on the Y pipe to manifold let the back pressure escape. It will be loud but can could confirm a blockage. Actually now that I think of it the old shop vac in the tailpipe might work too, you should get solid flow out around the y pipe if you crack the bolts.

 

Independently I came to the same idea cracking those bolts and running it like you said, but the idea of a shop vac is a better one I think.

Those manifold-to-y pipe nuts and studs were replaced when my son and I rebuilt the engine 6ish years ago so they look like they'll come off pretty easily with a little penetrating oil, i.e., they have some scaling from heat but otherwise are not corroded at all, but will the gasket survive the separation or will I need to put in new ones?

I've experienced firsthand the effect of a clogged cat 35 years ago on a drive up to Mammouth in CA to go skiing. My buddy's '76 Grand Prix just up and died, towed it to a mechanic in Bishop who hollowed out the CAT to restore flow, and off we went.

 

OK, I finally pumped a bunch of starter fluid into the intake -- first thru one of the plastic vent pipes on the right side of the intake, then thru the throttle body (with it manually open).

Both times, the engine started right up, revved up to 3-4,000 rpm on its own, i.e., without any throttle feathering from me and compared to 1,500-2,000rpm when started without strater fluid vaporized in the intake, then after a few more seconds than without starter fluid vaporized in the intake, dropped back down to 200ish rpm for a few seconds with those 2-3 aforementioned weak misfires before dying.

I am guessing that the extended-runtime-with-starter fluid test demonstrates that I have neither an ignition nor a jammed up exhaust issue, right?

I was going to disconnect the y-pipe at the exhaust manifold flange and put a shop vac on the tail pipe to see if it pushes or draws air thru the cats, but am thinking now that maybe that's not my problem.

So I am back to the fuel delivery system or one of the other mandatory sensor inputs to ECU that are required to make the engine run.

Again, relative to fuel delivery, I tested pressure at the fuel rail and it showed 50psi when not running, but I did not check it when running to see if it suddenly goes from 50psi to low or zero psi during the current start-a-few-seconds-then-die sequence. So I will do this.

I will also check the relay to see if maybe it is sticking; it can't be any fuses, because if it was a fuse, it would even start at all, right?

The only other things I can see as causing my momentary-starting-then-dying issue would be the two sensors I haven't yet replaced but which I believe may also have a role in controlling fuel delivery: the camshaft position sensor and the throttle position sensor.

Any thoughts from the interweb? Have I dismissed the clogged cat converters hypothesis too soon?

 

Cam and TPS sensor won't do it, might run a little wonky but still run. Disconnect the MAF and see what it does.