I have a friend with a 1993 Mitsubishi Diamante ES. I did new plugs and wires (two wires contacts were not in properly and corroded, and one of the plugs actually broke when I took it out...ish...) and started it up and discovered another problem.

Occasionally, while it was idling, it would suddenly cut out and sort of stall, but recover in a second. When it cuts out, there is a click from over near the glove box area, which I'm assuming is the computer doing something. While it's half stalled, for that one second or so, the check engine light is on, and it goes back off when the engine recovers.

I know this car has had a little issue with the check engine light. Once in a while (not often), when starting the car up, the check engine light would come on....but in those cases, the engine did not seem to have any adverse running conditions. Turning the car off and starting it again would seem to remove the light.

After sitting a minute, the cut-out problem seemed to go away, though I did not want to continue running the engine with it doing that, so I did not keep it going for more than a couple minutes (the temp gauge was just starting to rise). I also have not driven it anywhere since.

I'm more of a Caddy person when it comes to knowing the car well, so this thing is a little foreign to me, and I do not know how to read the codes on it. If someone could assist me in what might be causing this, I'd be grateful.

Update: For diagnostic's sake, I drove it down the road a bit. It did happen a couple times while driving as well. It manifested as an rpm drop (I'd say 200-300 rpm), and one of the times I felt it jolt while doing so. The jolt seemed less when I was cruising back (sort of down hill continuously) with the O/D off.

OK, I've been able to duplicate the problem enough now to know it's the A/C compressor that's clicking...and I guess sort of catching and putting more strain on the engine than it's supposed to....so if that means the compressor's shot...or going...or it's just low on refrigerant?

do a compression test on the engine first

to check air con look for the dryer and a small sight glass rev the engine if you see bubbles the aircon has had a leak

the clicking is the engine computer unit or the fuel pump relay on the glove box side

you can glear the fuel pump relay by pulling the fuse out briefly while the motor is running that fuse is under the engine bay in a box

next check the condition of your battery ..if over two years old replace the battery

check the fuel filter ..see if it is clogged

lastly undo the battery terminlas for 2 minutes and clear the computers memory

if the problem remains then the computer on the glove side needs replacement or repair
that computer and the sensors controls the idle

Thanks for the reply. The battery, I'm not sure on. The car has actually died a few times recently, but I've put a multimeter on it with the car running and it reads steadily at 13.6 or so...so the alternator is fine...and after turning it off, I've seen it hold the charge, also using the multimeter...so that's another puzzle, but I don't think it's the cause here.

The problem definitely corresponds to the compressor. I got a long screwdriver and put it to the compressor and my ear, and the click/engine stall is definitely originating there. Perhaps that's also triggering something in the computer/fuel pump relay, but it seems to be more a result than the cause.

I doubt it's the fuel filter or the batttery because I've had the multimeter on the battery, and it's steady whil this is happening, except maybe a .2v drop because of the engine rpm. If it were the fuel filter, I think it would be more of an overall problem. This happens suddenly, then it recovers. The engine can rev fine...but hey, it's cheap, I might just replace it anyhoo.

Ok, I just checked the A/C...a sight glass :-D...marvelous...I saw it's purpose immediately after I cleaned the crud off hehe. Yes, I see bubbles...without revving the engine, it was frothy on top... so yeah, that must be the problem, but I would think when a compressor got to that point, it would have something to stop it from kicking on...oh well...anyway, thanks a bunch.

I have one question though...what made you consider compression a possibility? I'm open to learn, but I would have thought that too, would cause a more overall problem than a clear cut-out/revive.

Update: And to add insult to injury, despite clear bubbling, I don't see where it's leaking from...but with A/C, I kinda expected this. Oh well. Just no A/C for now, I suppose.

The only other weird thing is the idle isn't perfectly steady...tends to surge within 50-75 rpm, but I'm not so concerned with that one... Thanks again for the help.

To make sure it is the aircon turn it off or even remove the belt.

Rob

G'ah...well it's only half the A/C, it seems. I took it for a drive (with the climate control completely off), and that same click/engine rpm drop happens just once in a while. Sometimes the throttle response is a little weak, so I'm gonna investigate that fuel filter tomorrow.

Another strange thing is putting the climate control on "Eco" doesn't seem to disengage the compressor (judging from the action in the drier). Does this just use it less, or do I have another problem?

It just fooled me because it happened consistently with the A/C clicking when it was idling.

Anyway, I tried disconnecting the battery for a few minutes, and it did not fix the problem.

I'm not sure I fully understand the possibilities here, or just what the fuel pump relay's job is (besides the obvious). My guess is that the suggestion was the fuel filter could be clogged to the point of confusing the computer, and it clicks on/off for a moment? In any case, I'll see what I can figure out.

Ok I took out the glove box, and I've determined it is the fuel pump relay that's doing the clicking (put my hand on it and felt the click when it happened). Just to be sure, I unplugged it, and the engine died.

As for why this happens, I'm still not clear if it's filter, something the ecm is sending it and isn't supposed to be, or something else. In any case, I'll have the fuel filter tonight, and I'll post the results after I install it.

the air con has an cooling fan maybe the temp sender is causing the problem
or the throttle postion sensor

air con kicks in you seem to stall so something is not adjusting to the extra power to the engine when needed

compression test is reccomended before any tuming should be done on the V6

there is a fuse you remove for two seconds to de pressurise the fuel system when the car is running (fuse under the bonnet )fuel pump relay

Ok I put the new fuel filter in, and though it was needed (I noticed improved response), it is not the cause of the problem.

Sorry if this wasn't conveyed well through all my updating... But the A/C seems to be unrelated to the problem. It is leaking refrigerant, I believe, but I still have all the symptoms with the A/C completely off, except it just isn't as bad as with the compressor on.

So, to reiterate... The problem, updated, is that while idling or driving, occasionally there will be a momentary (about 1 second) drop in rpm, about 200-300. The click corresponds to the check engine light coming on, but the rpm return to normal in just a second, and then the engine light goes out. If the A/C compressor is on while this is happening, it nearly stalls, or can cause a jolt while driving.

The clicking is coming from the fuel pump relay, which I'm assuming is the box that I put my hand on and felt it under the right side of the glove box (had to take the bottom cover thingy off.

I don't know where the throttle position sensor is on this car, and I'd be happy to investigate it, but I don't think it's the problem since it occurs while idling with the throttle in the same position, seemingly at random.

It kind of reeks of some electrical or sensor problem, but I'm not sure how to proceed in narrowing it down...fuel pump, ecm (hope not :-P), the fuel pump relay itself, a sensor governing it...g'ah... Me no likey.

If you can borrow another battery for a while then you should try it as part of the process of elimination. Strange things happen with batteries that are on the way out.

Rob

Hmm, well if you think so, I'll give it a shot. It just so happens I have a new spare (what're the chances heh), so I'll try that later and as always, post the results. Thanks.

Oh while on the subject, could someone tell me where the engine grounds are on this so I can check 'em? :57:

you know your way around a car

this is the downlaodable repair manual it will serve you well

http://www.lisho.net/?page_id=3] for you it will be the tr/ts manual

dont know where your fault is


I will take some pics I have a V6 magna outside

Service manual?!! :banana: Aha...yes, I half guessed that was the TPS just from it's conspicuous location...but yeah, that would help immensely. dirtyhands, you're a gentleman and a scholar, thanks very much :beer: . Rob_D hats off to you as well. I know I'm not that active on here, mainly because I know squat about these things...so thanks again for taking the time.

If I figure out what the devil this is, I'll be sure to get back here and post if anyone ends up with a similar problem.

Haven't fixed it yet, this is just an update.

It was not the battery, shame about that... I tested the TPS as per the manual instructions, and I found that the circuit did not close as it should when the throttle closed, but everything else checked out with it. I was able to rotate it a bit, which fixed the problem, however the main problem seemed unaffected.

I also tested the fuel pump relay itself. There was one point where it is supposed to register 0 volts, but it did register some itty bitty amount like 0.03v or so... Could that tiny bit be enough to cause it to click/screw up as it has been?

I know that's the source, so if it's not the fuel pump relay, then it has to be either something sending an improper message to it, or wiring to it. I couldn't find a circuit diagram with the relay in it, but I'll keep looking.

may be i have the same problem but the deference is the click sound some times happen when i am on idling and in stop position and steer right in the first turn i hear one click sound so please please some one help me.please anyone reply on my e-mail (magedibrahim@hotmail.com) or send to me massage on the forum.thnx[COLOR=red][B][U][/U]

Mine will happen when idling as well...either one really. I found the blasted harness in the circuit diagram, and I'm currently highlighting the wires from it and trying to find every possible device that could be causing it. I don't think it's the ECU, because when I tested the voltage on the ALDL, it did not stay high, it fluctuated.

I am eyeballing something that can go to the check engine light though. It's just a bit confusing...I need to look up what a photo transistor is... Did I mention I hate electrical problems? .... I hate electrical problems :-D.

Well after all this crap, I think the control (fuel pump, etc...) relay is the problem all along. The test procedure seemed to check out on it, but I did the following experiment:

In trying to isolate which switch (there are 2) in the relay was the one clicking, I stuck the probes of my multimeter in the back of the harness that goes to the relay. I noticed a drop from 12v to 8v on the one which goes to the fuel pump, so I started looking on that circuit, but I don't see anything suspicious. The only thing between the battery (I checked grounds) power and that relay is the ignition switch...which I'm doubting is causing this...and other stuff on the circuit are the ignition coil, power transistor, then to the ECU...and even if they were amiss somehow, I don't see how they would actually take power away from the relay unless it were truly taxing the battery, which I doubt (especially since this occured w/ a new battery as well). Suffice it to say, the coil, etc... are not "between the battery and relay, just have the same source.

So anyhoo, I got that drop to 8v or so when the click happened, that was putting the multimeter on terminals 3 and 7 of the relay harness... I tried again with it on terminal 3 to ground instead, and I didn't notice the voltage drop when the click occured, so it would seem that the relay is still getting its 12v, but not getting to the other side of it, so to speak, which would indicate the relay itself is the problem... This seems pretty concrete evidence to me, but I still have a wary uncertainty hehe... I guess because it checked out with the test...but maybe it's just going...woe is me.

P.S. Hey, anybody know a site I can get Mitsubishi parts direct?

Well...drat... I'm wrong. Got another relay at the junkyard today...and so help me it was the only car in the yard (a 92). I put it back in, made it back fine without incident. Next trip, it did it again. So either something on the circuit is causing a power fluctuation...blast if I know what...or it's the computer...pfft... This would all be swell if there was money to burn :-D.

I'm just in the midst of dealing with a similar problem - engine cutting out intermittently accompanied by a clicking "fuel pump relay".

Curiously this problem first manifested itself when I was forced to run my '92 Verada (Diamante) on a sick battery. Replacing the battery appeared to help at first, but after a while the symptoms returned. It was also very intermittent/random, sometimes going for days on end without any hint of problem, then suddenly it would start cutting out. Towards the end when the symptoms appeared it would be prevalent enough to prevent the car from starting or running for any length of time but after a while, minutes in some cases, hours in others, it would come good again.

Everything I read pointed towards the ECU being at fault and the likelihood of another case of "bad caps". When I pulled it out sure enough there was a large blackened area on top of the PCB, probably charred electrolyte leaked out from the adjacent capacitor. There was also evidence of corrosion on some of the copper.

As you've found, the "fuel pump relay" seems to be a dual relay. I've identified two sets of clicks. The heavier-sounding one comes on when the ignition is turned on, and goes off about 7 seconds after the ignition is turned off. The second, quieter one comes on when the starter is engaged and off when the engine stops (or after a failed start attempt or when the ignition is turned off). I'm guessing that the "primary" one provides power to (perhaps) the engine sensors, and the secondary one the fuel pump.

I'm surmising that they're both controlled by the ECU, and that clicking noise is a result of the ECU microcontroller resetting. My money's on your ECU being faulty - save for a wiring fault of some kind.

If you hunt around you'll probably find someone who can test your ECU. However I just found one of those "U-pull-it" wreckers (in Adelaide, Australia) who charge $44 for an ECU. If you can find a sufficiently cheap one, it might be worth it just to try a replacement.

maryland

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