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Welcome to the ETCG forums. Your topic sounds very familiar from one posted over at Mazda626.net. If we couldn’t help you over there then the guys here are definitely the next step. They helped me after all. 🙂
All Mazda 626/MX-6/Ford Probe 2.0L (FS engine) have a non-interference engine. Mechanics love to try and tell FS owners they have an interference engine. The only 626 ever made that had an interference design were 2.2L European versions (to my knowledge) but those weren’t FS they were F2. From my experience they do it as an attempt to sell new timing belts even when they aren’t needed so take that advice with a grain of salt when you hear it. It’s either ignorance or purposeful dishonesty. Either way it sucks to hear a mechanic try to convince you that you’ve got an interference engine when you know you don’t. It’s not confidence builder in their abilities I can attest to that. Sounds like you know what kind of shape your belt is in so I’ll assume you know when is a good time to change that out.
Fluctuating idle could be attributed to an air leak, PCV valve, throttle position sensor, IAC, or worst case a PCM. 99% of the time it’s not the PCM on the 626 just FYI. We have really good PCM’s. Running rich and other symptoms you are getting after the car is warmed up might be an O2 sensor. You can pull some readings from that. It should be switching as most O2 sensors do between 0 and 1 volt. You said you have a CEL but did you check the codes? You have a 97 so that’s OBD-II you can get them checked at any AutoZone for free. Have you tried cleaning your MAF?
As for the rest of the symptoms I’ll let someone else take a gander at that stuff. That’s about the best I can help on that. I have the factory manual if anyone needs specs.
Thanks for the help and pointing me to the other forum, I’ll head over there and leaf through the posts to try and gleam some information. That’s interesting that you mention that, my bro told me the same thing ( he said flat out it wasn’t an interference engine)… but as I said I’m not surprised the tech/mechs lied to me about that… as I mentioned this garage is rather shady… at least they’re smiling while stabbing you in the back.
I have not tried cleaning the MAF, though I was under the impression that if there was an issue with the MAF I’d see issues acerbated as I was accelerating not the other way around, either way I’ll put that on the list tomorrow to do… after all, cannot hurt.
Yep it’s OBD II, and We had O’reillys pull the codes a while back but beyond the catalyst being below threshold I don’t remember the other 2 codes, I’ll pull them up again tomorrow and post.
Thanks again for the suggestions, much appreciated!
The most common causes of an idle issue are a vacuum leak or air in the cooling system. Here are some videos on how to deal with both, I would recommend starting with bleeding the cooling system just to get that out of the way and BTW you don’t need a bleeder valve those are just there to help you fill the system faster so just do everything else in the video the same. I often find particularly after cooling system work has been done (i.e. a timing belt water pump job) that the cooling system does not get purged of air which causes these types of problems.
Bleeding a cooling system
http://www.youtube.com/watch?v=zUpXgAJ1 … ure=relmfuVacuum leaks
http://www.youtube.com/watch?v=9CPqbaSgcok+*update*
It was really tough to tell if there was leaks on the vacuum hoses so I started cleaning and boy did I discover some stuff all over. We do have cracked vacuum hoses, a cracked distributor cap (inside on the tower, along with cracked contacts), and more corrosion over all the sensors and copper contacts. Popped the fuse box out of curiosity and almost ever single one of the fuses was heavily corroded with a few blown (AC and tail lights). A engine mount nut that is not fully touching the mount and is stripped… and we’re still going.
So really we’re back to square one until I can repair and replace this stuff, my next door neighbor who used to be a mechanic mentioned that it might be symptomatic (as you said DjDevon) of multiple problems/issues and there’s really no use in trying to guess until I replace the known issues (vacuum hoses, distributor cap and possibly the distributor as it has lots of wear and areas of white damage on the housing)
*edit*
Just saw your post Eric, thanks for the help, we do have a known vacuum leak (possibly many more since many of these hoses are losing their pliability and starting to crack and they are probably going around the same time) and to be honest I really needed to flush coolant a while ago. It’s not pretty. I’ll admit… I bugged out because I hate dealing with coolant and it’s harder to dispose of, but thanks to your comment/pressure I’ll hop on that.No worries, keep us posted on your progress after you address the known issues and see what you’ve got.
Interesting thread. Keep us updated and let us know what symptoms are left once the obvious issues are fixed first.
Yeah guys the 626, MX-6, Probe (all related) don’t have bleeder valves just as a heads up.
Sounds like you’ve got quite the gaggle of issues going on there TheArete. You’re right no sense in trying to narrow it down when there are so many issues you’re finding. Just knock ’em out one by one and eventually you’ll get closer to the culprit. RockAuto is a really good resource for 626 parts by the way. If you need any pages from the factory manual for the diagnostic processes just let me know.
*update*
Didn’t flush the coolant because it was raining, but I did get a chance to run some more diagnostics this night.Thorough clean of PCV, rattle check, and checked hoses for blockage (none), and checked for vacuum while engine running (Check).
MAF sensor and IAT sensor checked and clean (it was pretty much spick and span but I went through and cleaned it anyways)
Cleaned all vacuum tubes, replaced cracked ones and inspected intake all the way to the manifold. Check.
Removed fuel injectors and cleaned contacts.
Taped up Crank Shaft Sensor wires that had not been properly fixed and sealed (did not re-solder them) with Cold Shrink Electrical tape.
Replaced Fuses.
Checked Accelerator cable, tension is fine.Tests.
Ran a voltage leak test tonight, no visible voltage leaks, even after spraying plug wires and cap with water.
Ran a spark test on every wire, and with every wire we are getting spark.
Used a stethescope and listened to fuel injectors, they are all clicking away (working).
Voltage on battery with leads disconnected: 12.5 volts, right within specs.
Performed a vacuum leak test with Carb cleaner. Sprayed around vacuum line to valve cover, PCV, Intake, Lines to injectors. Nothing. Not so much as a chirp in RPMS. Two sets of ears and no discernible leaking or hissing sound anywhere in the compartment.
Performed a Power Balance test by unplugging injectors one at a time, equally significant drops in rpms (didn’t have a tach, or DOVM that can read exact change, but no noticeable difference in drop between cylinders).
Coolant test: Bad. Most definitely needs to be changed and flushed though it does not appear to have oil in it (didn’t test for comb. gases, and not really sure how to go about that)New notes.
Engine starts up and idles at 2000 rpms stabile and then soon starts loping, or surging erratically. However after this starts and stalls out, or if I turn off the car and I immediately restart the car… it will almost immediately start surging again. The longer I wait… (cooler the car gets) the longer it takes for the car to start to surge (which sounds like a coolant issue).When running car in short intervals (such as for this test) of less than 5 minutes… no white smoke, in fact no smoke at all appears.
Continuity check on the ground… no continuity anywhere in the engine compartment. Checked Continuity from neg terminal to fuse box ground for shits and giggles… nothing… interesting indeed. Once again, heavy corrosion.
Installed 30amp fuse for AC. Installed neg. lead onto battery terminal and started to install positive lead. Lead made contact with terminal and lots of visible electricity arced to the terminal (we could here something trying to turn over, starter maybe?) and BAM!… blown 30amp fuse. So now we know why that fuse was blown, something is definitely not happy. Possible cause of my parasitic draw? Bad relay?
Next on list:
Flush Coolant system (Priority)
Replace fuel filter (no worries not throwing parts at it, it’s way overdue) and check Fuel Pressure (regulator doesn’t seem to have any external damage)
Check 02 sensors.
Check and Clean EGR, FIAV, IAC
Disconnect exhaust system to see if any improvement in engine running (thinking blockage somewhere, and not necessarily in the cats).Also, anyone have some tips on reading wiring diagrams… feel like I’m looking at a space shuttle ignition system…written in Russian.
You could remove an o2 sensor to see if you have a back pressure problem or use a gauge specially design for this purpose.
If the 30amp fuse is blowing right away, you have a short to ground. You need to figure out if its a ground side issue or feed side issue.
I’m going to post some video’s on doing some basic testing for you, particularly voltage drop testing. That is the better ways of checking the integrity of a circuit.
Voltage drop testing (on a no crank vehicle) –
http://www.youtube.com/watch?v=ry68G0C2Fyc
Short finding –
http://www.youtube.com/user/realfixesre … ZrCrBx4uFY
Fuel pressure regulator failure –
http://www.youtube.com/watch?v=AKtR_yF7 … 4eIEvQMlS_
Hope this is a starting point for you.
what is the 30 amp fuse that blew marked? if you can see what that fuse powers you can go to that device to check.30 amp is going to be a big load
like a starter. good luck and keep us postedWiring diagrams have the primer to them in the front of the booklet. At least they do for the 626 wiring diagram booklets (which is a separate booklet from the service manual). If you are beginning to learn wiring diagrams it’s best to have that primer you can flip to. Definitely cuts down on the learning curve.
As for the performance issue I’d be looking at the IAC next especially if it had been sitting for some time, I suspect it’s wide open and not regulating the idle as it should, you could try ‘tapping’ on it while the engine is running to see if there is any change in the idle if there is then you can reasonably suspect that there is an issue with it.
As for the electrical issue it does sound as though you have a dead short somewhere possibly with the AC clutch (not uncommon for something that sat for a long time), I would just leave the fuse for it out for the moment and focus on getting the engine running before you worry about the AC. BTW you should always connect the negative cable last to avoid those types of issues, the fuse would still have blown but there would have been much less arching.
I do plan on doing videos on reading wiring diagrams in the not too distant future.
*Update*
Here’s the next big rush of Info.Fuel pump… for the longest time I thought it was dead, or in a time continum, you could literally have the cap off and your ear against the filler neck and hear nothing when turning the car to “on.” Jumpered the diagnosis pins and kept it going with outake hose (back to the tank) removed and gasoline poured out. reinstalled plug and listened very hard and sure enough… the tiniest of all whrrrsss.
IAC– Okie dokie, tapped on the IAC and the throttle body which the IAC is attached ontop of and no change in speed or rpms. Resistance read 8.8 ohms, w/in specs. If removing the IAC plug during idle, idle immediately becomes erratic as it should (not the same eratic as when it surges, a steady sort of up and down).
MAF– B+ to Ground we are reading almost battery voltage of 12.06 w/in specs, and back-probing the MAF while in “on” position gives us 1.28v w/in specs, while at idle it smoothly goes to 2.17volts, and when reved up to 2.8/3volts, all w/in specs. When rpms are increased it optimally should read about 2 volt difference not 1 but thats still okay. MAF cleaned again.
TPS- No visible damage. Getting .484volts (1/2 volt) from the ground and signal, which is perfect. Reading 5.0 volts reference which is perfect. *Edit* Sweep test gives me constant positive readings from .5volts up to 4.3volts at WOT.
Power Balance Test #3– We are getting a drop of 450-500 rpms across all cylinders while under load (2500 rpms), by disabling Fuel injectors 1 by 1.
Fuel Injectors– Nice crisp clicking on each one which follow the rpms as they go low and high when revd. No difference b/w the 4.
Fuel pressure regulator test #2– slight smell of gas on vacuum tube, maybe one drip over a 5 minute run, if diaphragm is torn it is minimal and not affecting the mixture as unmetered fuel.
Fuel pressure– the new gauge is reading zero despite fuel OBVIOUSLY running, so we’re thinking dead gauge. Even fuel relief pressure valve does not release fuel on gauge, so exact psi is on hold till we get a new gauge (we used gauge on the intake and outake with both reading 0 during “on”, idle, and reved). Manually opened valve and fuel did spurt out of T connection during idle that was placed on intake line past fuel filter but before the rail. *EDIT BELOW on NEW TESTS*
Coolant- Removed radiator and flushed it as well as the engine block both ways, very little crud came out, though when I removed and cleaned the reservoir there was quite a bit of crude. Did 3 bleed cycles of about 20 minutes each and massaged the hoses (causes suction which can dislodge air bubbles) and got all the air out. Last run had zero air bubbles rise in funnel even after massaging the hoses vigorously (in, out, heater core in/out). Coolant hydrometer reads MUccchhhh Bettter now ;D.
Compression Test- Cylinder 2 did have some gas in it during the testing. Use a lil 10w-30 oil for wet testing in each cylinder. New spark plugs look good still.
Cylinder 1: Dry 180, Wet 185 psi
Cylinder 2: Dry 175, Wet 180 psi
Cylinder 3: Dry 170, Wet 185 psi
Cylinder 4: Dry 175, Wet 180 psiJust as a reminder. Erratic idling after car warms up, once it warms up we get random and erratic idling. IF I turn off the car after the erratic idle and immediately restart the car it immediately jumps back into surging. The longer I wait for the restart the longer it takes to start surging again. High idle as of now when I first start the car (1500rpms to 2000 rpms) though it does hold steady during this period. During tests the idle sometimes will hold steady if I jump on the throttle for a bit and then go wacky or sometimes stall out, other times only surge from about 300-800 and other times 100rpms to about 1800rpms.
Battery Voltage is still reading 12.6volts.
Previously did a battery Voltage Leak test, not so much as a single spark.
Getting spark across all cylinders.
Vacuum test with carb cleaner and no change in rpms.
PCV is working and in good condition.
Fixed cracked or missing vacuum hoses.
All Fuses have been checked and only the AC 30amp fuse as an active short.
Fuel pump relay is working.
New Valve Cover Gasket, no leaks into spark plug holes.
IAT sensor working and clean.
New Timing belt and water pump
New warm up catalytic converter and rear converter
New NGK platinum tipped pluggs recommended by my manual, same as previous plugs (except platinum tipped).
Distributor has one tower contact chipped but otherwise decent condition.
New Air FilterOriginally a check engine light when I first had the issue but has not been one for over past 4 weeks. Only receive a check engine when I unplug the injectors (duh). so currently THERE IS NO MIL/CEL.
No more white smoke from exhaust, my feeling is it was either oil dripping from the previous bad valve gasket or antifreeze that dripped onto the exhaust.
List to do is wearing short.
1.Clean EGR
2. Check 02 Sensors
3.Replace Fuel Filter
4.Check timing of Engine
5. Check Valve ClearanceAnd first up is to Pull up stored codes
Thanks for Sticking with me guys, much appreciated and sorry this is kinda a text/test heavy car.
update #1204
New Fuel pressure Tests–
1st test- 33 psi on idle, up to around 38 psi when WOT, and goes down to about 31 psi after the car starts bogging down. Remains at 31 psi even 10 minutes after car was turned off.2nd Test- 33 psi on Idle, up to around 38 psi when WOT and went down to 34 psi after car starting bogging down. Remained at 31 psi even 45 minutes after car was turned off. Both Test are w/in specs (should be no less than 30 psi and no more than 38 psi)
*Edit* With regulator vacuum hoses disconnected we get a rise of psi to 42, w/in spec. Almost certainly not a fuel issue from here to the tank.
14.57 volts on battery while running and no significant drop when it begins surging.
Removed 02 sensor. Idles high still and then when it begins bogging down you can distinctly hear a “brrp brrpp” a second before it bogs down…. then it goes back up and then immediately preceding any more bogging down by about a second you hear what I presume is a misfire/s. Any other explanation for hearing this? It’s not extremely loud or high pitched, more of a low sort of cough or sputter.
*Edit* removed Intake up to throttle body including IAT, MAF, and the main vacuum hose from the valve cover to the intake and a smaller line from the intake to the EVAP system, with the O2 downstream sensor still removed. Throttle body looked clean on the intake side and really wasn’t bad (a lil carbon buildup) on the other side of the butterfly plate. Cleaned Plate and body.
Removing Intake sensors/ hoses obviously caused a rough idle BUT… no more surging, and the biggest fluctuation I saw was about 200 rpms. No more high idle, started right up around 1000 rpms (which is were it was before this whole thing began). The sound out of the O2 hole greatly diminished. Thoughts? We’ve checked the MAF but maybe there is still something in that system beyond the checks I did. Maybe in the harness (the conductor) between that and the PCM?
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