irocwagon

91 camaro. 350 tbi,5spd
car was running fine, now it surges bad under hard acceleration,has severe explosive backfiring...unplugging the tan and black wire connector under the hood and the car is drivable,under acceleration check engine light cuts off then back on..codses 42 and 23..new coil, ignition module,plugs cap and wire

irocwagon

Just took a ride .shifting under 2800 it runs fine..cruising at 50 with no isuues...but hard acceleration and the problems start

RFmaster

Check your fuel pressure.....

//RF

irocwagon

new fuel pump,thought that was part of the problem

irocwagon

could a knock sensor cause these problems?

torque_is_good

does it occur when engine is cold, only in closed loop, or both scenarios?

Fast355

iTrader: (2)

Check the pickup coil/ignition module connection for correct orietation. It is possible to reverse the pickup coil connection and have the module retard the timing on acceleration rather than advance it.

irocwagon

i thought it wouldnt start if reversed{pink and white wire?}

temp doesnt matter, does it always,closed loop also

Schurkey

Backfire out the throttle body (intake system) or out the tailpipe (exhaust system)?

Backfire out the exhaust may indicate misfire; the misfiring cylinder(s) push the full charge of fuel and air into the hot exhaust system, where it's ignited. Won't take much and the catalytic converter will be broken or melted. I've seen mufflers blown apart from exhaust backfiring due to a faulty diverter valve on the AIR pump, when the mixture went rich as the throttle closed, and the diverter valve dumped air into an overly-rich and hot exhaust stream.

Backfire from the intake system could be lean mixture still burning lazily on overlap, igniting the fuel/air in the intake manifold; or it could be wiped exhaust cam lobe(s) leading to excessive residual exhaust in that cylinder(s). Another possibility is a burnt intake valve leaking combustion gasses into the intake manifold.

If the vehicle was in my driveway, I'd be doing a compression test, cylinder balance test, and a leakdown test to verify valve sealing and equal cylinder power at idle. That also allows me to inspect the spark plugs. After that, it's Scan Tool time, looking for short- and long-term fuel trim abnormalities; or anything else in the data stream that seems suspect.

Fast355

iTrader: (2)

Not sure where you are finding a white and pink wire. All the pickup coils I have played with are white/green wires. The pickup coil plugs in on the internal side of the distributor, not external. You have to remove the cap to access it.

irocwagon

ok,was thinking ignition not pickup.. thought you were talking about the wires on the outer,ill check under the cap,

its a massive backfire, seems like both, but deffi the tailpipe..only does it if tan and black wire is hooked up..

Fast355

iTrader: (2)

If the pickup coil is reversed the timing will be about 20-30* off and if memory serves me correctly the higher the RPM the greater the error and the worse it runs.

irocwagon

how do i determine if its installed correctly and not reversed other than swapping it around

irocwagon

also, the car starts every time the first time

Schurkey

Have you ever been inside the distributor to CHANGE the pickup coil wires?

If so, I'd be looking to see that the white wire was connected to the "W" terminal, and the green wire was connected to the "G" terminal.

RBob

iTrader: (1)

Connect a timing light to #1 plug. Open the EST/BYPASS connector and start the engine. Verify that the spark advance (SA) is at 0* BTDC (stock).

Turn off the engine and leave it at key-off. Reconnect the EST/BYPASS connector and start the engine.

Check the timing again with the light. The timing mark on the damper should now be more advanced then 0*, likely around 18* BTDC. This has the timing mark on the damper moving toward the passenger side of the vehicle.

If the timing mark on the damper moves toward the drivers side the pickup coil wires are backwards. I've seen this with brand new pick up coils.

RBob.

irocwagon

will attempt tonight..also new distributor and pickup, few months back

irocwagon

man im scared to reconnect that..last backfire it was in the garage when it happened,it knock the dust off the walls,went from being clean to complete dust covered

88chevycamaro

Any update on the backfiring? I seem to be having the same problem as you and cant figure it out...would apreciate some help!