My car is hard to start. It turns over for ages and then when it does get running, it misfires for a few seconds kicking out black smoke from the tailpipe before it starts to run smoothly. When it is running it performs well and idles smooth but it stalls without warning when idling. I ran a check on the computer and I get code 53 which I gather to be over-voltage (checked, fine), VATS (which is odd as it starts eventually) or EGR solenoid (not sure what to check). Has anyone else had a problem like this and if so how did you fix it? Many thanks, Matthew. (P.S. this is after I changed the coil and plugleads, it still smells rich)

Can't recall at the moment what code 53 IS, but I do know it's not VATS (code 46), or the EGR solenoid assembly (code 32). I'll take a look and see what my 92 FSM says... It may be over-voltage, but it's been so long since I got that code (bad alternator regulator) that I've forgotten which one that one is as well.

A guy said it could be one or more injectors playing up so I will test them tommorow, apparently they should be around 10 ohms?

No less than 11.4 ohms or they need to be tossed... Also make sure you have power to both banks as they are on separate fuses.

Are there any new codes?

:edit: And yes, code 53 is system over-voltage. If you checked that and it's good, it's probably an old code you can erase, but you will need to fix whatever is causing your driveability issue first or the computer will learn bad values when you do the idle relearn, which is mandatory after disconnecting constant power to the ECM.

Thanks for the info, do you know where I might find the fuses that control the injectors?

Through a bit of Googling I found a way to check the general resistance value of the two individual banks of injectors using a block behind the air con unit. Apparently if I get less than 4 ohms on either bank I need to lift out the plenum and do each injector and guess I'll replace any injector under 11.4 ohms.... Could be a good excuse for the 2.9 ranger injector swap!

What's this idle relearn you talk of?

Regards, Matthew

The fuses for the fuel injectors are the FP/INJ1 and INJ2 fuses in the fuse panel under the steering column.

The injector resistance info is correct... Don't probe the yellow and purple wires in that connector unless you want to test the coolant temp sensor as well.

The idle relearn procedure is something the ECM goes through to learn the proper settings for the idle fuel delivery and idle air controller position. It's a real pain, but it has to be done when you disconnect the battery.

Oh I see, so I guess it's something the ECM does itself then?

Going to do some diagnostics tommorow then and will post up how I go!

The idle relearn does require driver input. Do a . I know there have been at least half a dozen questions on this in the last month.

Fuses belled out ok, and got 4.5-4.6 ohms for both banks so looking good on that side of things.

Hmmm, what to check next? I'm getting the car towed to a garage in two weeks to have a specialist look at it but I would kind of like to find the problem myself / with the help of the internet! :P

I found the idle relearn stuff by the way... man the stuff you learn when your car goes wrong!

Well, now that you know how to do an idle relearn, try doing it. Disconnect the battery to get rid of that code 53, and go through the idle relearn. That might do the trick, or you might end up with codes that actually mean something.

I think I'll give it a shot but like you say, after I've sorted this driveability issue. I drove it a lap around town half an hour ago (needed to move it but my street is one way) and it broke down, probably a few people laughing at the American car being pushed by a bloke in his slippers!

I heard that sometimes the ICM can give rise to intermittent misfire/stalling problems so I've got one on order and shall see how that goes ....

I'm not sure about the 92s, but there was a TSB for the ignition system in 91 regarding intermittent stalling. Had to do with electrical interference on the black wire coming out of the ignition module to the ECM, or chafing wires in the same circuit.

One thing I should mention, my Camaro is a 1991 and not a 92 like my name suggests, that may have been an error on my part haha. Any TSB's may not have reached my car's first owner as it was brought to the UK and never driven in the USA so it's worth me checking out

I cleared my ECM the other day and when my car stalled out today I ran some codes.

Again I have code 53 which I take to be system voltage high / VATS / EGR solenoid.

Now I am also getting Code 15 - Coolant Sensor Circuit, low temperature indicated. I wonder if the ECM thinks the temperature is low and is dumping in too rich a mixture?

Regards

Matthew

Ugh... I already told you that code 53, for MFI vehicles (not TBI, not carbureted) means high voltage sensed (17.1 VDC plus for more than 2 seconds during run time), and this can KILL your ECM, ignition module, and pretty much anything else electronic in your car that's important (radio, VATS module, etc).

Since you now have a code 15, use a DMM and check both the voltage at the battery and the resistance of the coolant temperature sensor (to the right of the thermostat, 2 wire thing). Battery voltage should be no more than 15VDC, and the resistance of the CTS will vary with ambient or engine temp, but should never be open (no reading... yes, zero ohms is a reading).

Yup 0 ohms would indicate a short, believe it or not I am an HV electrical engineer but I have to say I'm not much of an expert on automotive applications... good job this forum exists eh?


Regards, Matthew

Oh, and don't forget to check the voltage reading between the green and black wires at your MAP sensor that's bolted to a bracket on the cowl lip by the heater/A/C box.

Hi

Light green wire (middle pin) to black wire = 0V

Light brown wire (end pin) to black wire = 4.99V

Wiring wasn't too clean so struggled to see the colours :P

I'm guessing the 0V from the green wire could be an issue?

Matthew

I forgot to tell you the engine has to be running when you take the measurement at the green wire. You have a good reference voltage, though, and that's another one of the big things.

Haha well the first step is to get the engine to run long enough to take a reading Lol... I was reading up on the MAP sensor, apparently if they fail they can cause overfuelling etc, though I would think I should get a code for that right?

Not necessarily. My MAF (same but different to your MAP) has been bad for quite a while now and I'm only getting a code 45 because it's reading 1/3 too high (around 50 Hz as opposed to the 32 it's supposed to read at idle). I've only ever gotten a code 33 once, and that was before the last time I reset the ECM.

Also, my 92 FSM says code 53 is caused by a reading of 16.9 VDC for more than 2 seconds at the ECM... Just making sure I don't point you in the wrong direction.

Well unfortunately I never got the car running to check the voltage... though there is a lot of moisture where the ECM sits....

Anyway the car has been towed now so we shall see if my mechanic buddy can find the issue!

Will post if a solution is found

Matthew

Haha, yeah me included, its not really that hard to do, and it does make a difference.

Just thought I would provide a little update on this one

The local garage informed me my new plugs weren't getting a spark dispite a strong spark at the leads, and that the performance coil might have caused them to fail. A new set of plugs was installed and the starting problem went away, but the intermittent stalling continued.

Today I replaced the coolant temp. sensor and took it for a test drive - no stalling or spluttering.

The old sensor at room temperature reads around 1kilo-Ohm less than the replacement and changes consistently with temperature. Weird huh???

Are you running an Accel POS coil? If so, junk it. Those things are barely useable when new, and definitely not on a DD. They overheat way too easily and short out internally to the iron core. I have one of those $45 paperweights in my garage because I thought it might help... After about 3 weeks, the problems only got worse because of weak spark.

That's interesting you mention that. Just shows the insulation resistance on those things must be diabolical. Mine isn't the ACCEL model, it's the Summit one http://www.summitracing.com/parts/SUM-850012/ but what isn't say they aren't badly produced pieces of crap too?

A stock unit has been ordered

I believe Accel makes the Summit parts... I had a thread a while back in which I got a response that basically said that about the only decent replacement coils were MSD Blaster coils, and they need to be placed as far away from the exhaust as possible.

Got rid of that Summit Coil the other day, still having problems though! Coolant temperature sensor checked out ok. It seems to idle fine then just shuts off like someone has turned the key.

Any further ideas folks?

Have you checked the wires coming off of the distributor module for problems? How old is the module? What color are the spark plugs? What kind/brand of plugs are you running? Test each of the plug wires, and the coil wire, for resistance. None of them should be above 10K ohms per foot (20K ohms for most of the wires). What's the resistance reading on the CTS when cold?

Just a little update for anybody interested/having similar problems. The mechanic called today, he had hired in some diagnostics equipment and managed to run the car for 1.5 hours by simulating the coolant temp. sensor with a costant resistance. So he recommended I swap out my cheap CTS so I have a Delco one on the way.

Maverick H1L : I never got a chance to check my leads. They were brand new although I couldn't say for certain they were all at the values they should be.
The coolant temp. sensors (old and new, both Standard make) both checked out around 3.99 kilo-Ohms at room temperature but I have a Delco one on the way to try.

Regards, Matthew

I hear you there. Mine's only a couple weeks old, and I'm going to have to opt for the AC/Delco CTS that's almost $15 more (got the cheapest one on RockAuto).

The "Standard" one is £8 here (stocked in the UK) and the "Delco" one is £25 (stocked in the US). What has always surprised me is the big gulf between good and bad parts for American cars. In the UK a part is a part, but with the parts I've bought for American cars you do seem to get what you pay for!

Update:

I talked with the mechanic who has the Camaro. Every time he checked the ECU for fault codes, he was getting a different one each time. So I contacted an American car specialist, who recommended a replacement ECU.

I have the new ECU (PROM chip to swap from existing ECU) so hopefully he will install it soon.

Is there any important information he might need to know before performing the swap? He's an accomplished technician but I'm just thinking of any potential setbacks that could arise as the result of swapping the ECU???

An idle learn will need to be done once the new ECM is in place. The idle learn is required whenever the ECM loses battery power.

RBob.

The mechanic needs to check the resistance on pretty much every computer-controlled solenoid on the engine and associated controls. Some replacement computers list a minimum of 20 ohms resistance per solenoid, but I am not sure what the specs are on most of them. There is a thread kicking around by Gumby that describes a problem with the driver chip for the evaporative emissions (charcoal) canister caused by a low resistance in the solenoid control circuit, which has killed 3 computers on his car so far.

Also, have the mechanic somehow check for an AC (alternating current, not air conditioning) voltage coming out of the alternator, which can wreak havoc with the ECM and ignition module (this killed my latest ECM, #3, back in March).

what input are you refering to?
i cant find a thread and have a lose of search words
when i replaced my battery i knew it was reseting although
i did not know she required my attention
learn.see.something new everyday

i ran into a similar problem with my 91 3.1
although she didnt smoke
now i have six new injectors
it was worth the 900 bucks
she is really really fast
680+for the injectors...i wish i had upgraded
140 labor + the gasket

The car needs to be put in Drive and the brakes held to keep the car from rolling, and the engine may need to be restarted if it stalls while the computer is learning the idle speed settings, plus the engine needs to be turned off and restarted after the radiator fan turns on and then off again.

how bout the importance of this step
should one repeat the entire process when this step is not taken?
everything seems fine except for my code 32 and
i dont even have an egr

It is a pretty necessary step to ensure that the car idles like it is supposed to. You can let it relearn by driving it around a bit but it will run and idle like crap until it does.

Just been in to see the Camaro at the garage. They hired in a local diagnostics specialist. Looks like he tracked it down to a bad connector on the PCM! Car wouldn't start at all until he gripped the wiring on the connector, then he could pretty much make it stall on demand by releasing it.

As for the rogue trouble codes, they've cleared up with the new PCM.

I've just been looking at a wiring diagram for the ECM connections. Does anybody know why the connectors on the ECU are labelled with an extra letter?

For example, connection C11 is the 11th pin on the 'C-D' block. But it is labelled for some reason as "BC11".

It's like some kind of prefix, but I don't understand what it is supposed to mean. The prefixes are either B, D or G. Any ideas?

The first letter is for the connector, the second is the row, and the number is the pin number in the connector. Should be BA1, BD11, and GE14, for example. I'd guess that "B" means "Black connector" and "G" means "Green connector", but that's just a guess.

Thanks for the info,

Not long til I get the Camaro back now

Matthew

Well the fault still exists. I noticed with the ignition turned on (but not started) there is an audible electrical 'fizzing' noise. It seems to be coming from a small metal clad module pushed way up behind the dash on the passenger side (near the PCM but closer to the dash).

Can anybody tell me a) what does this module control, and, b) is it normal for it to emit a sound like I described above?

Matthew

Can you get either a pic of the module thing or a pic of the connector for it?

Sure will do.

Something else I noticed, all the relays on the car were clicking in and out rythmically for a few minutes after the car stalled. The diagnostics guy had told me for some reason the PCM was pulsing it's outputs on and off intermittently.

The battery has been suffering recently, and sometimes won't provide any cranking power but will work fine a few minutes later. Do you think a weak battery could affect the operation of the PCM in the way described above?

Check for corrosion on the engine grounds and the junction block on the passenger's side of the car, where the ECM and fuel pump (same constant power circuit) get their power, and also the fusible links on the starter for corrosion. My 730 would do the same thing after the engine died, but if I waited a few minutes for whatever to cool off, everything was fine. I'm still scratching my head on that one, and I'm going to try my second engine harness whenever I get my body work finished (going to be a looong time for that).

Hi

The grounds all checked out to be OK when the technician looked at it. I am fortunate in that the guy working on it is very enthusiastic and has taken all the diagrams etc away with him to study.

I guess all it would take would be a piece of harness rubbing somewhere and you could easily ground out the injectors and flood the motor which seems to be whats happening... too much fuel for the ignition system to cope with!

Aren't cars fun! Really appreciate the help though

Did either of you go through the injector harness to make sure nothing is rubbing? How's about testing the injector resistance to make sure there isn't a shorted injector?

I know you're having fun with yours, but you should see the rust I'm dealing with and the crap I'm going through just to get access to fix it. The rear axle is hanging in place by 1 freaking bolt right now that refuses to come out of the pass side LCA at either end, and I need to get the axle out to get clearance for things like the fuel tank and the inner section of the wheel well I'm going to have to repair.

Argh! Managed to get it home today no problem. Tried to start it later and... very lumpy idle, and plumes of unburnt fuel. Code 53 keep recurring despite the charging system functioning correctly. I am at my wit's end with this car. It seems to pick and choose when it wants to start acting up, and cant seem to decide whether it wants a really high idle or just to dump massive amounts of fuel in the engine!

Maverick H1L - the injectors and harness checked out OK.

Matthew