The car has about 44K miles. I just had the water pump and OptiSpark replaced. The problem did not exist prior to that work. After the engine warms up it happens fairly consistently during acceleration from 2.5k RPMs on up. If I back off on the throttle, it seems to mitigate the problem somewhat. Check engine and ASR lights come on sometimes when the problem occurs. I haven't checked for any codes yet. It doesn't occur when the engine just idles.

Friends have suggested fuel pump or fuel injector.

Any suggestions or pointers to other relevant threads in the forum would be greatly appreciated.

 

Get the codes and post 'em. Much easier to gain direction that way.

 

Doesn't sound like injectors, it sounds more like ignition problems. Where did you get the Opti from, and is it vented? A lot of people complain about those optis being bad from the start.. try returning it and buying a different brand. Money is on it being faulty, from what I hear MSD makes a good product so give them a try.

 

Check the codes, it makes sense if it started after you changed the opti, then that is the place to start.

1. Connected properly
2. broken wires
3. installed correctly
4. check any sensors or wires that you disconnected or touched.

 

It's real easy to put it in wrong and have it pop and backfire !
I know first hand ! LOL

I'll see if I can find the bible post for ya !

New laptop had to do a search !

http://www.impalasuperstore.com/nais...TOPIC_ID=30984

I would do a couple of recommended mods like putting a fitting on the WO weep hole [ a 90 degree ] and hanging a hose down past the opti so in case WP fails you don't loose the Opti.
I used a plastic vacuum fitting cause i could not find a fitting.
I'm going to drill the ball out of a grease zert and try that.
Another thing is remove the coil ICM combo and put a couple thin flat washers between the IAC and the plate to allow air to cool it and get it away from the heat of the head.

 

Thanks for the quick replies and the link to the previous optispark post. I'm off to get some coeds ..., I mean codes.

 

By any chance did you also recently replace your air filter with a new K&N?

 

Why was the opti replaced? What brand rplacement? Who did the work?

 

OK. Here is an update. First to answer a previous post, the local GM dealer did the opti work. I replaced the opti because I was replacing the water pump and just had both done at the same time.

I have not replaced the air filter any time recently.

I just took the car to a friend who has an OBDII scanner (Actron) and he connected the scanner to the OBD port under the dash. The scanner could not read the codes (kept displaying an error when trying to read). On the way to my friend, the car exhibited the problem like it always does. After trying to read the codes, on the drive home, the car drove beautifully, no problem. I even decided to extend the ride to see if I could cause the problem. Took it on the highway and let it loose with some reasonably aggressive acceleration. No problems. Since this problem started, I have never been able to do that. Now I am thinking maybe it is an electrical problem. Perhaps the ECM? Any thoughts?

Thanks again for all of the comments.

 

Your 95 has a OBDII connector, but the computer is a OBDI. Do a search om 95's and you will see how to read the codes.

 

I would be taking it back to the dealer to resolve the problem. I ‘m sure they charged you a pile of money and it should be right. You should not be trying to fix it even though there is good information on the Forum.

As said it is a OBD1 system. Although there are some imbedded OBD2 codes , a OBD 2 reader will not work. You would need a Tech 1 or 2 (etc) that reads OBD1 codes, but has the OBD2 interface connector. Aside from that the on board diagnostics will read the codes as well as a scanner. Learn how to use the built in testing, it works great.

Aside from that I don’t think you going to find this problem using a code. There is no concrete broken part, signal missing that the computer (PCM ) is going to pick up. Bad fuel pressure, injectors, ignition wires, poor plug connections, or bad cap in opti will not register a code because they are subtle problems and basically the engine is running OK, just not right.

I only said this for information purposes only.
I’d be dragging my wheels back down to the dealer.

 

witch years are the first obd1 have been introduced...

 

I think 1981 at least for an answer for GM. Another generic answer is the early 80s.

Not sure when the vette got it but I know my Tech1 software goes down to 81.

 

where are you located?

 

pr0zac I am in the St. Louis area.

 

May sound stupid but I would check the air inlet on both sides of the Mass Airflow sensor. Just make sure the clamps are tight and not drawing in air between the MAF and throttle body.

 

Have you pulled the codes yet?
There are atleast 3 threads about how to pull codes on a 95 w/paper clip.

 

I don’t want to be the party pooper, but am I missing the point or big picture. I know everybody wants to help and give advice which is why we are Forum members and that is great.

He elected to take his car to the dealer for repairs which is fine and his prerogative. If there is a problem he should not have to fix his own car. I’ll bet he spent near $2000 for an opti and a pump. And if it is the opti, then what’s he going to do.

They should handle the whole thing and resolve the problem. Always act professional but be firm.

 

Again, thanks for all of the comments.

I do intend to take it back to the dealer, but I would like to be armed with as much information as possible. I did get the codes out today via the paper clip method and they are:

H34, H22, H64 and H67

I don't know how long these codes stay in memory, but I have had the TPS sensor replaced (H22) and I had a previous problem fixed where there was a short in the AC compressor (H67). Could those codes still be there? Also, I know that my Cats are not functioning. I believe the air flow through them is good. Could that be the cause of H64?

 

Well, here is the list of codes for your year. Looks like the TP sensor and MAP are throwing errors that might be linked. I recently replaced my MAP which cleared up a lot of missing (It had a poor seal actually). The O2 code is most likely just the result of other issues.

1994-1995: Diagnostic Trouble Codes
DTC #11: Malfunction Indicator Lamp Circuit.
DTC #13: Bank #1 Heated Oxygen Sensor #1 Circuit:
DTC #14: Engine Coolant Temperature Sensor Circuit Voltage Low.
DTC #15: Engine Coolant Temperature Sensor Circuit Voltage High.
DTC #16: Distributor Ignition System Low Pulse.
DTC #18: Injector Circuit.
DTC #21: Throttle Position Sensor Circuit Voltage High.
DTC #22: Throttle Position Sensor Circuit Voltage Low.
DTC #23: Intake Temperature Sensor Circuit Voltage High.
DTC #24: Vehicle Speed Sensor Circuit.
DTC #25: Intake Air Temperature Sensor Circuit Voltage Low.
DTC #26: Evaporative Emission Canister Purge Solenoid Valve Circuit.
DTC #27: EGR Vacuum Control Signal Solenoid Valve Circuit.
DTC #28: Transmission Range Pressure Switch Assembly Fault.
DTC #29: Secondary Air Injection Pump Circuit.
DTC #32: Exhaust Gas Recalculation.
DTC #33: Manifold Absolute Pressure Sensor Circuit High.
DTC #34: Manifold Absolute Pressure Sensor Circuit Low.
DTC #36: Distributor Ignition System High Pulse.
DTC #37: Brake Switch Stuck On.
DTC #38: Brake Switch Stuck Off.
DTC #41: Ignition Control Circuit Open.
DTC #42: Ignition Control Circuit Shorted.
DTC #43: Knock Sensor Circuit.
DTC #44: Bank 1 LF Heated Oxygen Sensor #1 Circuit Lean.
DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich.
DTC #47: Knock Sensor Circuit Or Module Missing.
DTC #48: Mass Air Flow Sensor Circuit.
DTC #50: System Voltage Low.
DTC #51: EPROM Programming Error.
DTC #52: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #53: System Voltage Low.
DTC #55: Fuel Lean Monitor.
DTC #58: Transmission Fluid Temperature Sensor Circuit Low.
DTC #59: Transmission Fluid Temperature Sensor Circuit High.
DTC #62: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #63: Bank 2 RF Heated Oxygen Sensor #1 Circuit Open.
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
DTC #66: A/C Refrigerant Pressure Sensor Circuit Open.
DTC #67: A/C Pressure Sensor Circuit Sensor or A/C Clutch.
DTC #68: A/C Relay Circuit.
DTC #69: A /C Clutch Circuit.
DTC #70: A/C Clutch Relay Driver Circuit.
DTC #72: Vehicle Speed Sensor Loss.
DTC #73: Pressure Control Solenoid Circuit Current Error.
DTC #74: Traction Control System Circuit Low.
DTC #75: Transmission System Voltage Low
DTC #77: Primary Cooling Fan Relay Control Circuit.
DTC #78: Secondary Cooling Fan Relay Control Circuit.
DTC #79: Transmission Fluid Overtemp.
DTC #80: Transmission Component Slipping.
DTC #81: Transmission 2-3 Shift Solenoid Circuit.
DTC #82: Transmission 1-2 Shift Solenoid Circuit.
DTC #83: Torque Converter Solenoid Voltage High.
DTC #84: 3-2 Control Solenoid Circuit.(Auto Only).
DTC #84: 2nd And 3rd Gear Blockout Relay Control Circuit.
DTC #85: Transmission TCC Stock On.
DTC #90: Transmission TCC Solenoid Circuit.
DTC #91: One To Four Upshift Lamp(Manual Only).
DTC #97: VSS Output Circuit.
DTC #98: Tachometer Output Signal Voltage Wrong.