Pulsating RPM- updated with pics!

[m0nkeyprince]

I was on the freeway when i felt the engine hesitate a little bit , at first i thought it was the road, then it happened, again and again, then when i pulled to the exit, the rpms just kept on pulsating like bouncing from 500rpm to 750 rpm, a "room roooom rom rom room room" sound. It made it one of the scariest drives home ever because the power kept going on and off and on and off. Seems like it happens more on the low gears though, i dunno.

I just replaced my evap canister and added a new battery, and just had my smog check done, everything was okay.

Any suggestions?

PS during the smog check the mechanic said something was wrong with my timing, said it wasnt 15 degrees TDC but when he went on the computer to prove it, the computer said 15 degrees TDC and he said nvm.

edit:

I now think its the distributor bearing thats failing, it was coined the "red death" when i did soem research on google. anyways, i took a look under the cap and rotor and heres what i saw

[Towncivilian]

Try cleaning your throttle body & MAF sensor to start with.

[zach7685]

I second this^. MAF can cause a whole lot of symptoms while setting no codes.

[m0nkeyprince]

hmm i checked the maf, nothing looks broken nor dirty, ill try cleaning it. But now im thinking of a clogged fuel filter, because of the previously charcoal leaking evap canister

[Towncivilian]

A clogged fuel filter generally does should not impact idle much due to less fuel pressure required to maintain idle; a restricted fuel filter would be more noticeable when trying to accelerate hard. But it's cheap, try replacing it anyway.

[909QX4OWNER]

My 98 QX is in the shop right now for this, They told me the MAF sensor was really dirty and I need a new distributor. Ant input of a good price for this baby ?

[Towncivilian]

My 98 QX is in the shop right now for this, They told me the MAF sensor was really dirty and I need a new distributor. Ant input of a good price for this baby ?

OEM distributor cap - $30.69
OEM rotor - $8.49

See this guide for replacement. You can clean the MAF yourself with some MAF cleaner (don't use anything else). Remove the MAF by unscrewing the 2 T20 Torx screws securing it, then remove, clean, let dry, and replace.

[m0nkeyprince]

okay, so i looked at my distributor, underneath, there is a fine coat of brownish red dust (sort of looks like brake dust) in the cap and on the rotor, i though, well, i will just replace my cap and rotor, but it looks like i have to replace the entire distributor assembly as the bushing is going bad, so called, the "red death".

Any body else heard of it?

[m0nkeyprince]

update thread with pics!

[m0nkeyprince]

so before i buy a new distributor, i would like to know if that brown dust is normal, any of you guys, or gals, willing to check for me?

[m0nkeyprince]

also, which section is the distributor found in in our FSMs?

it should be in electrical right?

[Towncivilian]

The index of the FSM only says EC-22 for anything regarding the distributor.

Sorry, I have no idea of the significance of the brown/red dust. I know next to nothing about distributors.

[fueler]

are you throwing any codes?

my dizzy went bad at about 175k miles. Well, the dizzy was actually good but the camshaft position sensor within the dizzy failed, and the only way to replace that is to replace the entire dizzy.

Hook up an OBD scanner to see if there are any stored codes (even if there are no CEL's, you could still have stored codes.)

Check everything you can for misfires... could be anything.... just the other day i found a bad spark plug wire and it didnt even throw a code... i just heard a misfire and started checking everything, found a wire that wasnt making good contact with the spark plug.

What im saying is it could be anything. Check the engine, hands on!!

[m0nkeyprince]

thanks town civilian for checking, it talks about the distributor, but i was hoping more of like a detailed cut out like the FSM has on the alternator

it wouldve been nice to replace the bearing grease with something that packs a bit more durability like mobil1 grease or royal purple UHP grease

and fueler- nice to see youre still checking on the forums! now to hear from emptyV and Pwnin O'Brien

i have replaced the fuel filter so far, no difference, im going to take a video later on to show the symptoms

i was pretty hands on in making sure all the connections were tight etc. so far, no codes, and the only anomaly is the brown dust under the cap

if im right, the only dust should be silvery, from the cap contacting the rotor, and brown=bad distributor bearing=replacing entire distribtor.

The camshaft position sensor i heard was a cheap piece, and held on the distributor with screws, but they dont sell that separately, that was on the Mercury villager forums (they use the same distributors as pathys and qx4s)

[fueler]

and fueler- nice to see youre still checking on the forums! now to hear from emptyV and Pwnin O'Brien

heh, a bunch of OG's have fallen off... my BMW is now my #1 squeeze but i still push the QX4 daily since you can't trust a BMW. I had a misfire due to bad plug wire... bought a set of plug wires but was too lazy to change them all so right now it's running with 1 new plug wire hahaha



If u had a bad cam position sensor, it would throw a code specifically for it.

What spark plugs are u using? I once had a misfire from using bosch plugs. Always use NGK

[m0nkeyprince]

im using NGK laser iridiums along with their wires

i have no codes, all green across the board which is weird. i dont think a bad distributor would throw codes

btw fueler, have you had a chance to look up the part numbers from your all weather mats? im still in need for a perfect fit rubber all weather mat, you can pm me

[909QX4OWNER]

Update : So the shop tells me they cleaned the MAF, in return the truck runs alot better. He told me it needs a needs distributor, tried a cap, no go. The rpms were bouncng around a little. Once they replaced the distributor all is good. Funny story, I recently bought this used. He showed me the old cap, it was not factory. It had, " 98 QX4" written on the side with a silver sharpie pen. Looks like it was pulled from another, not factory !
Now I'm having AC issues. Shop tells me I need a new lower hose and recharge. Telling me $225 for this. Think I'm going to buy hose myself ( they wanted $88 to replace, I found for $42 on internet) the rest is to charge system. Anyone used the nifty refills kits they sell at the auto shop for $30-$45.

FYI - The distributor job cost me $350

[m0nkeyprince]

lol i got a new reman OEM distributor for $211 with free 2 day shipping on amazon

i wouldve gotten a brand new non reman. distributor but they only sell remans, even at dealerships.

by the way, our oem distributors are made by hitachi

[m0nkeyprince]

FIXED!!!

The problem turned out to be the distributor, I think the bearing was burnt out, as when I turned the old distributor upside down, brown dust came down

link to distributor thread here (where I will also link the How to guide):

post6330592.html#p6330592