I have seen a few threads with problem similar to mine but most of them end without telling the world what fixed their problem.

Theproblem: The car is a non-supercharged model and it does not accelerate unless if I push it very slowly. If I put the tranny in hold mode and shift manually then I can get it to accelerate pretty well after about 2500 RPM, but as soon as I put it in "D" the same issue begins. The idle is smooth but if I time it right and do a sudden WOT while idlingit will exhibit the acceleration problem.

The signs: The CEL (light works fine) did not come on and there were no codes when I bought it (I bought it with the problem). The TCS On/Off light and the ABS light stays on. The coolant reservoir shows bubbling on the side opposite the cap when I press the open the throttle.

What I've checked:
[ul][*]The car does not overheat as indicated by the temp gauge and computer read out using ELM 327 scan tool. Max temp I've noticed is 205 F.[*]The oil is clean and so is the coolant. The coolant will overflow from the reservoir after the car warms up and then it empties out when the car cools down asking for more coolant.[*]The factory manual troubleshoot guide has the accelaration problem and I've followed it to no avail. Everything checks out as described. I was not able to check the powertrain as described and I have only taken the readings at the sensor and not the ECU.[*]I've checked the MAF and is good. I've cleaned it as described in other threads and it made no change.[*]TPS is good. I've replaced it with another with no change. I've even left it unplugged once accidentally and no change was observed.[*]Cleaned the throttle body and the IAC and no change.[*]Cleaned out the EGR and itspathway and no change; although there is no signal coming to the EGR solenoids. The solenoids test fine.[*]I tested for vacuum leaks with propane, starter fluid, electrical cleaner and found none. The Elm scanner shows LTFT to be around-9 during idle so definitely no air leaks.[*]Compression is around 170.[*]Knock sensor resistance checks out.[*]Coil resistance test is good. I pulled off a boot from the distributor and held it on the tower. The spark is good but thins out during acceleration. The STFT goes positive when I unplug the boot and keep it away from the distributor. Does this mean that the injector also turns off?[*]Spark wires were internally broken and were replaced. No change.[*]Spark plugs look nearly new and PCV operates fine.[*]Fuel pressure is at 36 during idle and dead heads at 70. FPR works fine. Fuel filter has been changed out. Short distance driving while the pump is dead headed improves the acceleration quite a bit but for 100 feet or so.[*]I took the injectors off and did a flow test. They flow equally and are within spec as listed in the book.[*]The LTFT is -4 while driving but oddly goes to +24 as soon as I put it in reverse.[*]I have replaced two pre-cat O2 sensors using Bosch because the heaters were no good.[*]The Elm scanner shows that the non-continuous monitoring systems for catalytic efficiency, O2 sensor, and EGR is no good. The computer goes into closed loop in matter of seconds after I start it up cold. Is this normal?[*]My pre-cats were knocked out by the previous owner so that explains the catalytic efficiency. The main cat was plugged and I have temporarily removed it and all the downstream exhaust piping (sounds really good). No change in performance.[*]I hear this suction sound from the hunk of IM metal in front of Spark Plug 5. I am considering this to be normal since leak tests and Elm reading don't indicate a vacuum leak.[*]I've had P0301 and knock sensor circuit code at different times but they have not returned after clearing them.[/ul]
Not checked yet:
[ul][*]Timing belt stretch/alignment[*]Powertrain[/ul]
I am totally stumped and frustrated. When I bought it the spark wires had been crossed and that melted the main cat. As noted above I have temporarily removed it. I don't know what could be wrong with this car.It looks good and handles well so I'd like to get it fixed up.

 

The car will also have occasional afterfire and Idon't know where to begin for the powertrain.

Before I replaced the plug wires I could read high voltage from the distributor even when the volt meter probe was 3 inches away from the distributor cap. After I repalced the wires I read high voltage if I touch certain parts of the outside of the distributor cap but not away from it. Replacing the cap did not make any difference. When I do the same test on other cars there is no high voltage reading outside of the distributor whether touching the cap or not.

 

The TCS/ABS lights should be the first priority as the TCS will retard the timing so as not to spin the wheels. Most likely the control unit. Anyway,tackle that first as it can effect performance greatly.

 

I connected the TBS to GND at the diagnostic connector but only got a solid ABS light. Can the ABS codes be checked by light flashes or do I need special tool like SSTs.

 

No special tool needed. You can use a jumper on the drivers firewall diagnostic connector. Theres a long thread on this forum on TCS issues, You should read through those. If you have TCS and ABS it is all incorporated into one control unit under the left side dash.

 

I checked the voltage at each terminal on the TCS Module. The motor relay and wheel solenoids gave me 0 V(FSM: Relay or solenidON =0-2 V, Relay off B+ or ignition ON B+ for the solenoid). I had the ignition ON so I guess the relay was ON, but not sure if the solenoids should be ON. If the solenoids were only supposed to read B+ with ignition ON then that did not happen. The fail-safe relay showed B+ which is a malfuntion according to FSM. I'll be looking into this. The wheel solenoids should be B+ . I've got a '96 book and using it on '95 car. The wiring is slightly different. I think 1I and 1K are actually 1H and 1L in the book, respectively. Would be great if someone can confirm this.

I checked the timing belt alignment without taking anything off and prying the belt covers at the cam shaft sprockets.Both cams line-up on compression when the crank is at -2 degrees (at the timing marks), so the belt is aligned properly. The disty rotor is just passing the number 1 tower terminal when looking inside the cap. No problems in these areas.

I'll be concentrating on the ABS/TCS unit starting with fail-safe relay. I can't get the ABS to flash me a code(s). I followed the instructions on the other thread on this forum and the FSM (both are same).

 

I checked out the fail-safe relay. It is part of the ABS relay (2 relays in one). They both are good. When I turn the key ON they click and then click again and go off. When I ground the terminal 2B on the module the relay kick in and both my TCS OFF and ABS lights go out. I tested the main relay the same way and my ABS motor comes on.

Also did a resistance check on the ABS solenoid valves and they are good.

The question now is what is causing my relay to go off?

2000SMazda had a post where his engine performance improved after changing the timinig belt. The issue was that the timing belt stretches while under load; hard to believe that it'll stretch enough to cause performance problem. My issue is somewhat similar. I'll have to do the replacement but little later. MX6.net had a thread about the ignition module going bad. Same type of motor as millenia so that is something I'll also have to check.

 

sounds like a timing issue. check the timing belt marks, if the intake cam is off, it will idle smooth, but no power. the backfire is also a sign of retarded timing, as is the no power. the ign distributors are a big issue on these engines. i am only guessing, since we dont have the n/a motor.

 

I checked the timing belt marks and they do line up. Since this car is a DOHC but each bank runs off a single cam pulley, is it possible that the pulleys line up but the individual intake and exhaust cams may be off inside the head?

The ignition condenser appears to be dead. I intend to replace that and see if that makes a difference. Being able to read high voltage outside the distributor cap tells me there may be a problem in this area also. Autoparts, dealer, and ebay turn up nothing when trying to look for this condenser so I am going to have to get a closest match to this from a different car.

 

The left rear wheel speed sensor was bad. After replacing both my TCS OFF and ABS lights went out. The engine performance still did not change. Locating the ignition condenser has not been easy. I am trying to locate something in equivalent value (0.47uF). When I find one I'll be sure to post.