Very Odd Operating Conditions, Poor Acceleration, Please Help Options

[Starcelica101]

My problem with my car started One morning in May 2008 when I started the car and then it had a prolonged stall and shut off. After this incident the car doesn’t cruise like it used to, accelerate like it used to, and the car continues to shake, Has a major increase in gas consumption, 23 MPG as opposed to the 30MPG I used to get. And doesn’t startup, or shut down like it used to. Every 4th or 5th startup the engine has a split second jolt like shake. Compression on engine is 175 psi for each cylinder and had leak down test and held pressure.

My RPM tachomoter needle is slower when comming down after accelerating and even bounces a little when it is down to 1000 rpm and the engine sounds like it lingers when I reach a high speed as if it is still spinning and not deccelerating as fast as it used to ( hard to describe without you driving it). I changed out the spark plugs with various gapping but made no significant difference. Everyone that has looked at my car rules out vacuum leaks and exhuast restrictions, especially with a brand new catalitic converter. Keep in mind my Ignition system is all new including the whole distrbutor, wires, correctly gapped plugs, close to perfect compression with leak down test, Battery is brand new, and the Ground wires look mint and I even cleaned them at there contacts to make sure there was no corrosion and even swapped out my old distributor module with a new one and still made no change. ALL PARTS ARE OEM INCLUDING Map Sensor.


My mechanic also thought it might be the water coolant temp sensor or ECT but it is showing the correct feedback voltage on the computer, but I really think this may be the issue.

This morning I started the car when it was cold about 50 degrees outside. The car used to start at a high idle at 2100 rpm but this morning it started at 1800 rpm for 4 seconds then went immediately down to 1600 rpm for 3 seconds then down to 1400 - 1300 rpm for a few seconds, then went back up to 1500 then to 1800 then 1500 then 1800 then down again. Crazy but true, and it’s not the Catalytic converter, I had it removed and put in another! next few minutes as if the car wanted to go high but just kept getting bogged down. I tried messing around with different pcv valves too, I made sure there was no restriction in it and the pcv tube and the suction to the intake manifold is deffinately deffinately strong.


Also, the spark plugs that were just a day old were white in the middle but on the perimeter ring or bottom plate was totally carboned up with a dry sooty black carbon. My old spark plugs that were in my car for 3 years that I took out before I had this problem had a brownish copper like look to the ring or bottom plate surface that is now totally carboned up. Also, I am currently running with Desno plugs and NGK before that. But I tried out Bosh plugs a few months ago and the car would majorly missfire.

also, when driving into a parking lot and putting the breaks on abbruptly the engine almost seems like it wants to stall seeming like it stalled for 100th of a millisecond then ran at a lower rpm than it should have and the engine would majorly shake.

This problem occurs at both open and closed loop so I don't believe the oxygen sensor is the problem, however my assesment is if my open loop isn't fully engaged my car might not be going into closed loop and is screwing up my whole engine management system, making my transmission operate oddly as if the car hasn't warmed up all the way which is what it feels like. I did have the injectors removed to test the spray pattern and it sprayed well..

I had two dyno poles done on the car too, the Air fuel mixture was where it should be and it had exaclty the horsepower it should had but the torque as 127 when it should have been 117, so this is too high. This explains me having to floor the pedal down for it to torque when going up a hill, the sensation is hearing a bogging sound like a UURR sound from the hood and the RPMS will Keep going up with very poor acceleration, the engine starts shaking a little too(New Engine Mounts, Even Nuetralized the engine when intalling them), so While Im going up that hill and pressing the pedal down almost all the way and the rpm at about 3500 the car will finally torque going from 3500 rpm to 5500 rpm which is twice as high as the car used to do which explains the spike on torque on the dyno poles. The dyno pole lines were very Jagged too, which shows the exxessive vibration that was thought to be caused by a worn out transmission which is why I had a new one installed. I had brand new timing belts installed recently by the dealership since they thought the timing was off and it isn’t…ALSO, THE ENGINE IS SLOW TO DECCELERATED TOO, WHICH MIGHT INDICATE AN EXHAUST PROBLEM, THOUGH I DID REPLACE THE CATALITIC CONVERTER.

The transmission is totally new and so is the torque converter and PASSANGER axle.

REMEMBER THIS PROBLEM STARTED LAST MAY 2008 WHEN I DIDN'T USE MY CAR FOR 4 DAYS, WHEN I STARTED IT, IT RAN AT FAST RPM LIKE NORMAL THEN ALL OF A SUDDEN THE CAR MADE CLONKING SOUNDS THEN SPUTTERED AS IF STARVING FOR FUEL or a Clog OCCURED THEN STALLED, SO THIS CAN BE DESCRIBED AS A PROLONGED STALL. SINCE THEN THE CAR HAS BEEN TOTALLY BOGGED DOWN. MY ASSESMENT IS THAT WHAT EVER CAUSED MY CAR TO STALL THAT MORNING IS WHAT IS CAUSING THE POOR ACCELERATION AND DECREASED MILES PER GALLON OF 23 COMPARED TO 30 MILES PER GALLON THAT I HAD BEFORE THIS.













New parts installed after problem started:

1 Transmission
2 Engine Resealed
3 New engine and transmission mounts, They are neutralized and tight!
4 Map sensor
5 Spark plugs
6 Spark plug wires
7 The whole distributor including hull sensor, coil, condenser, cap, rotor.
8 IAC Valve
9 PCV Valve and tube
10 Intake manifold plenum Gasket , triple checked for leaks!
11 Catalytic Converter
12 Thermostat
13 Air filter
14 Fuel Filter
15 Cleaned Throtle body 3 times!
16 Serviced injectors 3 times! Even had it on bench to see spray pattern…
17 Battery Brand new
18 New Engine Hoses
19 Water pump
20 Timing belt, Timing has been checked 4 times!!!!!!!!!

Significant parts that are not replaced are the

1. Water coolant temp sensor
2. Throttle position sensor
3. Exhaust manifold
4. Main ECU, Never flashed original or reset it
5. Knock sensor or Cam sensor
6. original engine
7. Fuel regulator
8. Fuel pump
9. Oxygen sensors