I have an 87 Camaro with the 305 TPI. It has an intermittent engine fault which seems to generally only happen when the engine is warmed up. The problem occurs when cruising at speeds of 30-40mph and using light throttle, the car starts to buck and kind of surge, but this goes when I accelerate slightly harder. When its doing this the other issues I have are when I slow to halt at junctions at traffic lights, the revs dip right down and the car splutters almost as if its struggling not to stall and when I come to pull away there is a lack of power and it runs really rough. The weird thing is it doesn’t always do it.

I’ve changed the plugs, plug wires and used a couple of cans of injector cleaner. The new plugs and leads improved the overall running but haven’t solved the problem. Whilst reading through my Chilton manual I came across the section on the EGR and figured that this might be an issue.



Before I get too excited and pay out for a new EGR plus runner and TB gaskets (remember I got to order this stuff from the US) do these problems sound familiar to anyone?

BTW the ECU isn't throwing any codes!

 

You have some troubleshooting to do. Can you do perform any datalogs? I would not start throwing parts at it without real troubleshooting. Getting a copy of a Factory Service Manual or professional level manuals (Chilton is fine for getting the firing order and plug gaps, but does not have the detail needed for troubleshooting) , and a laptop with the ability datalog is almost a necessity for working on these cars.

If you have good reason to suspect the EGR, then it can be isolated by disconnecting the vacuum line to the EGR valve and plugging the supply line. If the problem continues, it is unlikely that the EGR is the culprit. That is a no cost test.

My car had a somewhat similar problem, but I did get an error code, so this may not be very useful, but the next test will not cost you anything other than a few minutes of time. A faulty idle air control valve with an internal short can cause similar behavior and mess with the ECM. A very easy way to check it is to get the car fully warmed up, then unplug the electrical connector on IAC valve and take it for a drive. If the problem goes away, you have isolated the issue, if it stays, it is not the IAC.

There are so many things that can cause the symtoms that you described, you really need to troubleshoot. A faulty injector(s), a coil or ignition module that is dying, leaking fuel pressure regulator, vacuum leak, mass air sensor with an intermittent issue, and electical short, ECM, clogged cat, fuel pump, etc

I am not trying to discouage you, just trying to show that methodical troubleshooting is the way to go, because there are a lot of parts (many £) that could be thrown at the problem before you find the issue.

Good Luck

 

Sounds like what my car would do when the MAF went out. Disconnect the MAF and drive it. If problem goes away, you either have a bad MAF or bad relays. Replace the relays first because they are least expensive. If still persists, you may need a new MAF.

 

I don't have any ability to do datalogs I'm afraid and at the moment all I've got is Haynes and a Chilton manuals, both of which are good for different things. I will look into getting a factory manual, hopefully they are available on eBay.

It is interesting that you mention that IAC because I noticed last night when I was taking a look that the coolant(?) hoses that run through the IAC housing have been bypassed at some point by a previous owner. Would this have any affect on the output from the IAC?

I take your advice on methodical trouble shooting, I can see how I would throw a lot of money at this problem and not get anywhere. I was hesitant to rush in and change the EGR because A) I could splend a load on bits and it could solve nothing and B) I could end up disturbing something else and putting another fault on!

Thanks for the help, I now have a plan of action!

 

I rather hope it isn't the MAF, but I guess that is another thing to consider. Could driving it with the MAF disconnected cause any damage?

Thanks

 

Don't do it for a long drive across the country, but doing it for a few miles won't hurt anything. It just affects gas milage. The computer uses a default setting with the sensor is disconnected. When replacing the MAF, best thing to do is replace the relays at the same time. The relays are a weak point in that circuit.

 

OK cool, thanks for the help.