My check engine light came on. The error codes are 1. faulty fuel injectors and 2 compensating for lean/rich fuel mixture. The car seems to be running normally on all cylinders, and does not smell rich. The vacuum line for the FPR is dry. I'm not sure where to start. I don't see how there can be anything wrong with the fuel injectors, as the car runs and drives normally. The only thing I've noticed is that the idle is a bit high.
I was thinking it might still be the FPR but I don't want to start buying parts I don't need. I have some older LH 2.? manifolds kicking around, are the FPRs the same as the 2.4 regulators? I'll get a new one if thats the problem, but I was going to try one of the old ones for diagnostics.
I've never had a LH fuel injection problem before so I'm a little lost. I've mostly had Kjets, which I prefer. I don't like relying on all the electrical components in LH.
Thanks for any help

Thanks for all of the advice. I cleared the codes this morning. The codes were 113 and 231. I drove the car all day and the light didn't come back on. Power and fuel economy appear to be normal. Also the idle is normal. The only thing I changed was the end of the vacuum hose on the fuel regulator. It was pretty lose, so shortened it a bit to get a good tight seal. So maybe the regulator was not getting full vacuum. I will read the 700 faq on diagnosis. After this experience I want to know more about the LH system.
It does have its original O2 sensor, but has a relatively new AMM installed at the dealer (by the previous owner). The stove pipe (preheater hose) disintegrated long ago so there us little risk of frying the AMM.

The first thing to do is to post the actual codes in a new post. The second is to understand that compensating rich/lean code(s) - typically 231, 221 are secondary and a response to the O2 sensor being on its extreme range (rich/lean) of being able to compensate. So, look at the primary code(s) first. I have the green book on the LH 2.4 system and it has a trouble shooting procedure for each code. I'll try to check back this evening to see what you posted.

Faulty injectors and compensating for mixture codes. The first is causing the second. If injectors do not fire correctly, fuel is not deliverd properly. No explanation because somewhere in the archives is an explanation, just forget where.

Probable cure. Disconnect battery.
Release, clean, reattach the following.
1.both computer grounds on intake manifold.
2.Engine to body strap at right rear of valve cover.
3.Battery negative where it attaches to block.
Reconnect battery.
Clear codes.

well who knows what year you got but first use denial reset by pullen fuse six or blade depend on year. don't buy any parts and dont think injecters are bad sometimes ecu gets wild correcting stuk in its brane needs to be cleared.

Just fixed the same problem in my 89 240, except i could tell it was running extremely rich and drinking gas like a lush. I'm no mechanic, but the first advice i got here on the board didn't fix it. But it may yours, so here you'll find my post and replys: http://brickboard.com/RWD/index.htm?id=886417

So I followed the advice and it didn't solve the problem. Actually testing the AMM and O2 sensor showed that they were indeed faulty, even though there were no codes for them. Look in the 700-900 FAQs for testing them. Before I replaced the AMM, though, I removed my faulty air intake thermostat that was responsible for constantly directing hot air through it. I just took it and the flapper out along with the hose and plugged that hole up since it's of no use for me here in Florida. (I've heard it's a cold weather thing for startups) And that seems to have solved it, although not a cheap fix since i bypassed the used AMMs on ebay for the auto parts store's $150 one. I'm still puzzled, however, by the 'fault in fuel injector' code.

Some other leads:
- check out the info in the 700-900 FAQs if you haven't yet
- if the AMM and O2 sensor are fine, i've read there actually can be a fault at the injector (leaking, etc, but my post from before has a good reply to how this happens)
- i also gave a decent cleaning to my throttle body without taking it off and replace the air filter

and some others i can't remember, but there's a lot of info here on the BB, both in the FAQs and the postings/responses.

Good luck!

If the idling is high have a look at the Idle Air Valve, an alloy canister under the inlet manifold. It is always worth cleaning out the valve with petrol - it soots up and classically cause the idle to be too high. I'm not sure that it affects any codes though.
I've very occasionally had a rogue code pop up with no apparent cause, which goes away for a few months if I just clear it. I am told poor connections and earths are always the first things to check.

Found the post for the long explanation.

http://www.brickboard.com/RWD/index.htm?id=884364