Mazda MX3 Hesitation Problems

[r l mcmichael]

Hey Yall, this is my first post. I love my mazda (94 Mazda MX-3 GS 1.8L) and its time for me to start working on it again, but... I dont know what the problem is. I changed the coolant temerature guage thingies by the coolant cap (there are 2 of them). I cleaned the throttle body a little bit and got rid of all the gunk, I cleaned out the Idle Air Control valve. I blocked the vaccum on the EGR valve and it seems to do nothing although I am curious if I would need to put a plate between the block and the egr valve too. I did buy a used replacement that I plan to use. Lastly I bought a used ECU that matches the computer in mine if worse comes to worse. What I would like to know is what do you think the problem is... this is what happens.

On a cold start when I rev up the engine everything works fine, there is no hesitation. However, when the engine warms up a bit more, when I lay on the throttle it bogs down and does this wunh wunn wun wun wun w w w normal revving. It usually does it in low rpms from idle to 3-4,000 rpms. Also, when I do a slow acceleration it does not do it. In a medium acceleration it is a hit or miss. - I will include a video link to youtube when I get home.

My thoughts are
-EGR
-MAF -Mass Air Flow Sensor


I checked
-Spark Plugs
-Distributor Cap
-Distributor rotor button

I dont have many tools to do expert work, but I was wondering if anyone had any other advice for me or thoughts on what the issue may me. I would greatly appreciate it.

-RLM

[mikeinaus]

could be your distributor on its way out. id also look into your o2 sensors.

to properly disable the egr you would need a block off plate. removing or plugging the vacuum line will cause the ecu to throw a code. there would also be no benefit to disable it if its not getting stuck open.

[r l mcmichael]

Do you have any ideas on how to check the distributor to determine if its dying? Also would any connections need to be checked that may weaken the distrubtors ability to "put out"? The positive terminal and negative terminals are on tight, but I wonder if there are any grounds that could cause these issues?

Everyone I've talked to has mentioned O2 sensors as a minor possibility, I'm beginning to think it may be the THE possible factor.

I just changed to the other used mass air flow sensor and the car is idling all the way at less than 100 rpm's. Could I do the Positive Negative pull and 15 Second Brake reset thing? Before the pull it idled around 1000 rpm.

When I post a video do yall think you could get a better understanding of the issue?

Also on a last npte sometimes when accelerating, on the decel sometimes the lights flicker. Does that shed light on anything or make it more confusing?

[mikeinaus]

distributors are common to fail on our cars. if you do a search im sure you can find more information about testing them. the main symptom of it failing is intermittent weird problems with the car at operating temperature. there is an HEI mod you can do that may solve your problem. again give the search a try there is a tun of info on distributors.

as for the o2s, i had a bad one that wouldnt throw a code but caused the car to skip and sputter at low rpm. any chance you would have access to a lab scope so you can do an accurate test on them? i normally wouldnt suggest replacing parts at random but if your o2s are old it might be worthwhile to replace them.

you can try and reset the ecu but most likely any errors that would cause this type of problem would come back pretty much right away.

[MrMazda92]

You might have better luck testing another distributor out, if you have access to one. Are there any MX-3 owners nearby that you happen to know, or are there any local to you on here?

[r l mcmichael]

Thanks for the advice.

I bought mine from a guy who I think he had more fun playing with the car than taking care of it, so I might need to replace to 02 sensors. The outside portion looks rusty. There is an issue where sometimes the check engine light goes on and off when acceleration and decelerating. Maybe there are multiple problems?

I wish I had access to another mazda mx3, but I do not. I live near Atlanta and Athens Georgia. If any of you know any local mazda guys I would appreciate it.

I just uploaded a video to youtube and will share it with yall as soon as it posts.

I will look up the HEI mod and see what you are talking about, but as of now I have no clue. As far as a lab scope, my brother in law is a doctor and I could probably borrow one of his, I have an MRI appointment tomorrow and I might ask if they have one lol. If not my bro-in-law might help me out. What would I be checking for with a scope?

I mentioned earlier that I reset the ECU before and then it helped it to idle better, but then I put in a used MAF and now it idles really really low. I was thinking a rest might help that because it may need adjusting since it is a new MAF.

Thanks for yalls help. I will keep yall up to date on it.

- Youtube Video of what it is doing. http://www.youtube.com/embed/CI9Xws5rBA0

[mikeinaus]

lol a lab scope is similar to a voltmeter where it displays the voltage readings in a wave pattern so you can see how they are functioning. i doubt a doctor would have access to one. proper o2 readings would be a steady wave up and down, a bad one would have sharp peaks and valleys along the curve.

have you tried pulling codes? there is a diagnostic box near your battery. you want to put a piece of metal (paper clip) between the TEN and ground pins. then turn the ignition on (without starting the car) and the check engine light will flash a code to you. long flashes symbolize X10 and short flashes = X1. example, 3 long flashes with 3 short flashes would = 33. if you do a search you can find more information about it.

when you find your codes post them here and we can give you more specific information.

edit: i just watched your video. thats a fairly substantial misfire. have you checked your timing? when you say you checked your plugs, disty cap and rotor did you replace them or just inspect them? if you havnt already id start with some new plugs, plug wires, cap and rotor.

if you have any mechanic friends it might be a good idea to have someone with a better knowledge have a look over. judging by how substantial that misfire is im doubting its your o2 sensors. im suspecting timing or possibly the vaf(Vane AirFlow not MAF) at this point in time. hopefully the car has some codes to give you a hint on where to start. i noticed in your video you have a spare vaf by the airbox, does the car run the same with both of them? can you confirm the code on them is JE50?

[r l mcmichael]

haha... whhhoooops. I thought you were talking about a stethescope not an oscillator.

When I first ran codes I believe I pulled a 27 or 28. I left the car at my parents so I will have to go back and check. The problem is that it comes on sometimes and not all of the time. I will do that next time I go over, unfortunately I am looking for another place to live for my next semester of college this week.

How can you tell that it is a misfire? Would you think a new fuel filter would help? If I could afford to put it in the shop to have all the vaccum and other odds and ends checked I would. As far as the timing, I have not checked it and do not know how without taking all the covers off... maybe I should spend an entire day on it. The car is off of insurance and has no tag, but I reckon I could temporaily insure it to have it checked. My cousin is a mechanic and I could take it to his shop for a look over if I insure it. There is a MX-3 at pull-a-parts that I could pull injectors out of if that is the problem.

Last thought on another problem, would my exaust system cause any issues? I installed iridium plugs once, but only for a short time because they were way too powerful I felt. Its been a long time now but I believe there was a backfire.

As for the MAF/VAF. Is that the difference since the sensor is built into the tubing? The spare one was the one I put in lastnight after the video. After I installed it it seems to run smoother but the idle has dropped all the way down to 100 rpms and cuts off after a minute or two. It still does the hesitation thing but it is more subtle but that may also be because I cut off the vaccuum to the egr. I was going to try to reset after I put it back in. I should really be more methodotical about this whole thing.

Thanks to yall's posts I have a better idea of what I need to do. Any ideas on other ways to check the timing besides removing the covers? I need to look that up to.

[mikeinaus]

ok the egr is a valve that lets exhaust gases back into the intake. if its functioning properly it wont cause any performance problems, it will actually slightly improve it if anything. if however it is stuck open it will let exhaust in at the wrong time and starve the engine of o2 during idle. i dont believe your problem has anything to do with egr. if you want to check its functioning properly you can suck on the vacuum line feeding into the egr. you should feel the valve open when you suck, it should then hold vacuum and stay open, then drop when you relieve the pressure.

to check the timing you need a timing gun/light, or you can pull off the timing cover and double check it physically. but thats alot of work and i wouldn't suggest it if your not that comfortable with cars.

i define a misfire as improper ignition of the air/fuel mixture. things like hesitation, skipping and that weird lawnmower sound yours is making i would classify as misfire.

the fact your idle dropped and the car ran alot better with the new vaf might be the answer. perhaps your idle has been improperly adjusted to compensate for the incorrect reading the ecu was getting from the vaf. when you installed the new one, the ecu read that and tried to correct the idle to what it believed is correct (this is a guess).

maf is a mass airflow, vaf is vane airflow. they both do the same thing but in a different way. your car is designed to use a JE50 vaf, installing a maf from a mx6 or another car will cause a bunch of problems as the signal it sends the ecu is codded differently.

its possible a clogged cat could cause problems similar to yours but im not sure.

how long have you had this car? how/when did this problem start?

i highly suggest to not just replace parts and hope for the best. thats a good way to burn alot of unnecessary money. we need to narrow this problem down to a smaller possibility of causes. engines need fuel, spark and oxygen to run. lets assume your getting fuel as your car is starting/idling and revving "relatively" fine. now we also know your getting spark because its idling/running. we dont know how strong this spark is. doing a tune up will remove that from the equation (for the most part). that leaves us with oxygen. in your case it may be getting too much this can be from a vacuum leak, or possibly an incorrect reading from the vaf to the ecu so the computer incorrectly calculates the air/fuel mixture.

start with the basics. give the car a full tune up:
oil/filter change
spark plugs
ignition cables
disty cap/rotor
fuel filter
id also double check the online manuals and make sure your vacuum lines are routed properly and that you dont have any major leaks.

i would then install the vaf that worked better, reset the ecu, try and set the idle then re-adjust the TPS. if that makes no or little improvement i would try disconnecting your exhaust in front of the cat and see how the car performs. if it revs normally with the cat disconnected its more then likely clogged and youd want to replace it.

this will get you a good base to start working from. if you know those didnt fix it you atleast have have something to go from. id then try and borrow a timing gun and double check everything is lined up properly. you could also pull a spark plug and compare the colour/strength of the spark of it running well compared to when it misfires. this should give you more information on testing the disty http://www.mx-3.com/manuals/showimg.php ... _G-027.gif

[r l mcmichael]

The latest updates is that I ran an ohm check on all of the injectors. All of them were 14.2.

I also redid the positive terminal cables and ran a second ground to the firewall. The car runs much stronger than before and is stable, it sounds beautiful, that said... it still has the same issue. There is a reunion here today and I was talking to my cousin who is a master mechanic. He recommended me replacing the sparkplug wires as the next step because he also agreed that there was a significant misfire/skipping. The old wires (i havent changed them since I bought it because the other guy said he had just installed them) are beck arleys? something like that. Never heard of them and they sound cheap. If i were to buy new wires would a recommendation of Duralast be ok? None of the shops I am looking at have any, but Autozone has a set for $60. He also recommended me getting NGK plugs for a mazda (the current in there are champions I believe. I had bosche ones in there before i took them out but I believe they were iridium and I pulled them an hour after installation. Too much power I felt like... is it possible they could have messed up the valve system and that is my issues?

-RLM

I've had the car for a little under 2 years. The problem started right around fall of 2010. I bought a truck and quit using the car, but I did drive it around the yard and let the engine run somewhat when visiting my folks. As far as the problem starting it just started randomly one day. I dont think it was soon after I used iridium plugs, but it could have been within a close time frame. Bent valves maybe? Anyway to check that?

My cousin checked the vaccum lines and thought that they were ok and there were no leaks. He said it is almost definitely related to ignition and fuel system. Thus is why i checked the injectors which all checked out ok. One of two of them may be dirty though. Im really not looking forward to taking them apart if one is dirty. What is the standard breakdown for doing injector cleaning?

Oh and in reference to your other post. I will do a full tune up in the next few weeks. I have a guy that is supposed to look at it this week but he never actually showed up

[Daninski]

Ok right off the bat I'd recommend you SeaFoam your engine. http://www.youtube.com/watch?v=2hrasAYG42g&feature=fvst
Disconnect the PVC hose and pour the SF in there with someone ready to give it a little rev if it starts to stall before you get 1/3 of the can into your intake.
Doing that alone could clear up some of your problem. Injectors may also be plugged, it actually sounds like it's only firing on 3 cyls. SeaFoam is cheap like 10 bucks, pour the rest in your gas tank to clean your injectors.
If you notice an improvement there's no reason why you can't SeaFoam twice.

[mitmaks]

hows your disty cap/rotor look like, if you can post some pics. I just read about your cheap spark plug wires/spark plugs. You do need to switch to NGKs, theyre good spark plugs and for spark plug wires go with NGK. There's member on here who is selling sets fairly cheap (check in FS section of classifieds)
Also make sure your spark plugs are gapped properly and use torque wrench when tightening them down.

[Ryan]

Alright.

The first thing I would do would be to rent/borrow a timing light.

You may not need to do any adjustments, just put it in diagnostic mode (jump TEN and GND in the DIAGNOSIS box), and throw the light on it. (sensor on cyl 1, point the light at the crank pulley where you can see the timing mark, which is a little tab on the timing covers with some graduated tick marks on it, if you don't know) If it isn't at 10º, try to put it at 10º by slowly rotating the disty (after loosening the two 12mm bolts holding it to the head). If its impossible to get it there, then your timing belt is on incorrectly.

Now, this is not impossible to happen on its own. The timing covers have this stupid little gasket that runs around the seams, and it gets old and pieces can fall off - into the timing. This combined with an old hydraulic timing belt tensioner can cause it to skip. I had a very similar problem on my black car before the swap, the timing was spontaneously out 2 teeth, and ran exactly like yours. Idled fine, had a rough time at high throttle (ie, high ignition advance) but would suddenly run like a dream over a certain RPM.

If that checks out, it is definitely ignition (ie, distributor) related. Stop troubleshooting fuel, you're wasting your time.

If it were a EGR leak it would run terrible at low RPM, I'd quit looking at that too. Easy way to tell though, is to take the vacuum line conencted to the EGR solenoid itself, and suck on it. If there is no leakage, the diaphragm is fine, and the solenoid is probably fine. If its stuck open, the car would run terrible at low RPM.

I also do not think it is O2's. The car will run fine on a base map if the O2's are out of whack enough to throw a code. You can try simply unplugging them and trying, but I seriously doubt they are the problem.

Champion is a shitty brand. Throw in the proper NGK's (BKR6E11). Beck Arnley doesn't make terrible stuff. If the wires look decent still (no cracking or falling apart at the seams) then I'd leave them too.


But seriously, check the ignition timing first. You will more than likely save yourself the rest of the headache and money.

[Daninski]

Ryan, with it running that bad do you really think he can get any reasonable timing reading. I do agree checking the disty cap. Look for dark lines (carbon lines) inside the disty cap, these will short out your spark. Funny thing is this started after the radiator change right so I'd be looking at what you tampered with doing the rad change. Is the disty itself loose and you rotated it by accident.

[Ryan]

yes, I think he can. If if runs stable at any RPM you can get a good reading.