I start my 1987 Camaro V6 Mpfi no problem. Start driving and occasionally the following happens. Seems the car misses a beat while cruising,idleing in drive, or in park and then it goes nuts. Car starts missfiring badly then stalls and wont start again for about 3 minutes. When it re starts all is fine and I can drive for hours.

I have replaced plug wires, 3 maf sensors,1 maf relay, 4 ignition modules, pick up coil,plugs, ignition coil, cap,rotor, and rebuilt the distriburator. I also blocked off the egr valve( this may or may not be a good thing but it seemed to solve the problem for a little while )!

I am at a total loss. Most of my problems have been caused by faulty new parts. Now when I buy new parts I have them check them before I leave the store. I ve already seen 2 new ignition modules fail instore.

P.S. The car is throwing no codes. Before it threw #42 and #34
which are EST and MAF. I replaced those parts and now those codes are gone!

Any and all suggestion would be great!

 

Have you checked the simple things during your tune-up like the PCV valve and gas filter and air filters?

 

Ah forgot to mention those aswell. All changed 6 months ago. Thanks for the thought!

 

my thought would be maybe something floating around in one of the injectors. i had something close to this before. it was junk in one or two of the injectors that would occasionally get in the way. i guess you could have them checked out. i also had the same thing w/ the ignition coil. have that checked again i guess. those are two possibilities i can think of.

 

could it be heat related? like vapor lock?

 

My vote is:

The air filters and fuel filters go bad all the time..If changed 6 months ago..I think its time for new ones..Second yes it could be vapor lock..Last thing...Major exhaust leak....

Matt

 

As for injectors, i thought of that to but it always happens just once then car is fine for hours as in three hour trips, possible but not likely!

As for heat related, my thinking aswell, but not once operating at temperature. I mean after it acts up it is fine even if it gets hotter. I thought maybe ignition module was heating up and cutting out. But car heats up again hotter when i start driving again and then it is fine. I am no expert when it comes down to it but I think it is something related to when the engine comes out of a cold start mode ( or whatever you may want to call it ).

Usually happens 10 minutes after start up if it does happen at all.
Car misfires and then dies. 3minutes later all is well. I think it has to do with a transition from cold to hot. I'm just not smart enough to know what is triggering it.

And once again thank you for all the advice. Whether it is useful or not I appreciate it!

My thinking of what I will try next is as I said I blocked off the egr valve, in the winter it was fine ( I was thinking it was faulty and injecting pure water into the manifold, I have had that happen on a different car ) and caused the same problems.

Now it being summer the water may run down the exhaust manifold and trip an O2 sensor and it may trip a rich condition then try to adjust either spark or fuel. So I will seal the manifold from egr valve but will vent the valve into the engine compartment. I hope someone wiser than me can say this is a good idea. Like i say I am just guessing. I have searched around here and havent seen anyone post with the same problems!

I guess that means I'm special ( but I wish I wasnt )

 

Hey camaro pimp! I will clean my filters but I doubt that is what it is. Its an intermitent problem. Starts great runs for ten minutes then dies! Then starts back up again 3 minutes later and all is fine. Same goes for fuel filter. I have seen bad fuel filters on cars before. Once car has acted up and i restart it I can go 100 mph
( actually probably about 90 its only a 2.8 litre )

I actually have 2 cars. One for winter and one for summer.1987 camaro for winter and a restored 81 Z28 for summer. My 81 has none of this efi ****. If it dont run its either dead battery, broken crank, or no gas lol!

Sorry had to add that. Maybe I should just drop a 305 in my car with a carb and distriburator and be done with it! Just that efi has so many sensors etc that can cause problems!

Thanks for the input though, like i say I shall clean the air filters.
As for vapor lock,lol. I live in Calgary Canada. The car should not be getting vapor lock in May! Were finally 10 degrees celsius here. 81 Z28 is another story, 35 degrees in summer, 10.5 to 1 compression and 16 degrees initial advance works out to hard starting when hot ( vapor lock yes ).

Not trying to belittle anyone just stating it as it is. I am a gearhead and not scared to get greasy and dirty. Just finding myself very old with this efi stuff! Hehehe I'm only 31!

 

sounds kinda close to a problem i had once. I replaced the o2 sensor and ignition coil because i didn't know which one was bad. that solved it.

 

Do you have the typical lose sloppy stearign wheel? It can make the key act funny. does 87 have vatts?

 

Already replace ignition coil but i will check spark again. As for o2 sensor, how do I check that?

The car does not have vatts and steering wheel and ignition switch is tight.

 

VATS started in '89, right?

Glad to hear you're a gearhead, that makes the explanations much easier. As far as filters and everything go, just check out this message and make sure everything's replaced ok: https://www.thirdgen.org/techbb2/sho...threadid=87334

You're running at 16 degrees advance? Wow. You're not getting any detonation problems, or destroyed spark plugs? Does the car run at stock timing? If not, it might be time to change that timing chain.

Have you popped a fuel pressure gauge on it? I don't know why pressure would drop after 3 mins, and then be fine for hours, but maybe you just have borderline pressure that gets affected when the car warms up.

How are the battery cables?

Did you clean out the IAC passageway and pintle? See here for details: https://www.thirdgen.org/techbb2/sho...hreadid=175177

You could check the oxy sensor with a voltmeter, but if you haven't replaced it yet, you might want to- the sensor (Bosch 12014) is only $20 US.

I can't see of a way that an EGR would inject pure water into the engine... as ya know, our EGR isn't mounted on the intake manifold at all (although the crossover ports are still in the heads, the intake manifold doesn't have matching holes). The only way for coolant to hit the valve would be if the head gasket blew.

But the EGR could have stuck open and caused a stall condition, EGR will only open when 3 things happen- car is warmed up, road speed is high, and throttle is low. So when you came off the highway and stopped at a traffic light, that's when the car would stall. But blocking it off would cut that circuit out entirely...

I doubt it'd be the TPS (throttle position sensor) but couldn't hurt to check it. Car off, unplug the TPS (3 pin sensor to the passenger side of the throttle body). Install jumpers between the TPS connector and the TPS sensor so all three wires are hooked up. Now clip a DIGITAL voltmeter (analog can blow the ECM) between the middle and top terminals of the sensor. Put the key on, read the digital voltmeter. Spec is 0.55 volts +/- 0.05 volts at closed throttle.

EFI's not that bad... I haven't had a factory sensor blow out on me yet, and I've got 269,000 miles on the motor. The only sensor I've changed has been the oxy sensor!

Oh- hey- not to skip the obvious, but have you checked the computer for error codes? Maybe one got thrown right before the car stalled out.

 

Thanks TomP! Gonna give your suggestions a try. As for the EGR I have not seen water injected into the manifold however on a previous car I owned there was litterally ice under the air cleaner.
Source was EGR. That was a dodge colt though not a Camaro!

AS for 16 degrees advance, that is on an 350. Timing is damn near perfect on that car. But I had to install an adjustable vacuum canister to prevent detonation. Timing is actually 10 degrees on this car! Unsure what the timing should be cause I have no decal.

IAC and TPS I must check, aswell as O2 sensor. Thank you for the link! To be honest Iwill have to do some reading about those sensors cause like I said I am a noob with efi.

Gonna take a test light with me so when my car acts up again I will check for codes immediately. Right now there are no codes but who knows it might throw one when it acts up.

I really appreciate the assistance wether or not it solves my problem. At least it gives me something else to go on. Also I hate taking my car to a garage. I take pride in the do it yourself thing.

As for having 269,000 miles and only one sensor dies your a lucky sob. I have 68,000 miles on my car and have had 3 Mass air flow sensors go and on my fourth ignition module ( mostly dues to faulty new parts ).

I will post my results maybe they can help someone else!

Thank you again!

 

Just thought I should update this thread with my results. After all I hate reading threads where the initial poster never tells what the fix was.

I have now replaced 4 mass airflow sensors, 5 ignition modules, and 3 ignition coils, 3 starters. My last battle with my car ended up being the ignition coil although it was really hard to diagnose.

I tested for spark when I was positive the car would not start. Damn car started and ran on 5 cylinders, plug wire back in and let car run till it died. I proceeded to do this 6 times because everytime I removed a plug wire to test spark the car would start. Finally it wouldnt, no spark at the plug, next i tested coil and had no spark. I reconnected all the wires then the car started again.

I must add I live in Canada and all parts were bought from Auto Value parts. Do not buy there generic parts buy all Blue Streak ignition parts or better. I have replaced all there generic electrical parts at least twice with the exception of the pickup coil which I figure will probably die in a matter of weeks. Since initially redoing my ignition system with there generic parts I have only put on 5000km on the vehicle but replaced 4 ignition modules, and 2 ignition coils.

Moral of the story spend a little more on quality parts.
Thank you all for your help!