Clogged Catalytic Converter?? Symptoms?

[Careless]

Sooo. Did a bit of searching here and on z31performance... couldn't really find enough info on anything similar.

 

I got my car on the road.

 

I'm burning something still. Doesn't smell like gasoline much, doesnt smell like coolant much, smells a touch like oil...

 

I'd put it somewhere in between rich condition and oil maybe. I did put a cup of seafoam in the crank case, and then I removed the oil after 1 hour of running (to break in the rebuilt turbo and whatnot) and then put in a new filter and new oil... so lately, it's been getting a bit thicker. I start the car in the morning and there's a puff. just one. for a couple of seconds. again, ran to it... doesn't smell like oil. If I drove well into the top of each gear (4000 ish, lets say) the stuff doesnt BILLOW out, but it does come up. It's not thick enough to billow, it just fills the air.

 

After i start it and give it a good 3 or so minutes to warm up a touch, I coast down the street. But it jerks and jolts forward and back. I tried easing into the throttle... still does it.

 

I remember the FIRST time i took it out around the block just 4 days ago it did the same thing and I had to really mash that throttle for it to make a loud POP sound and then it *beep* fleeeeewwwwwwwwww. I mean, if I put my foot down, once the hesitation breaks up, the car MOOOOVES, and I mean MOOVES... On the way home, I may have smoked the entire neighborhood.

 

I'm wondering if this is a symptom of clogged catalytic converters. I want to pay for my aluminum radiator this weekend so I'll live with the exhaust burning for a while... but today a cop looked at me a little weird as he drove by... kinda worried that it might be excessive. but around here I'm pretty sure only a Ministry Office can pull you over. But when that happens I have an open-to-air filter, stock pcv system removed, and egr deletion. that's like 600 in fines.

[Careless]

UPDATE:

 

just went for a midnight cruise before moving the car to park it. the hesitation is more apparent than ever before. cruising as normal in 1st gear and 2nd gear, i get a jerking motion from the car... a lot of misfires happening in the tail-pipe, and a raunchy smell.

 

at this point I'm not sure how to test for the catalytic converter. the AICV is opening on idle and the pipe IS hooked up to the exhaust feed tube, just to rule that out for anything.

 

at this point it's quite undrivable. but after it has a couple of misfires, the car jolts with a power surge.

 

jolt-jolt-jolt-move-jolt-jolt-move-jolt-move-jolt-mooooove-jolt-mooooooooooooooooove

 

is the best way to describe it.

 

checked the manifolds by lifting the hood and couldn't see any glowing. car started to get hot so I shut it off after a 3 minute wait to purge the turbo of hotter oil.

[Careless]

now she doesnt wanna rev much on idle and she does the same sputtering... and the car dies after sitting at 1000 rpm and then slowly dropping to 4 and choking itself. I think I'm going to punch the cat today. or remove the o2 sensor.

[dan5138]

Sounds like you are running way rich. Unplugging The O2 sensor wont help matters as it's probably narrowband. Sounds like your plugs are pretty fouled at this point too. I would start by checking your AFM and all it's connections. Also pull each plug and see what color they are. Soggy and black = rich. If it's more apparent in one cylinder, check injectors. Also try disconnecting your cold starting injector. Sometimes the temp switch for these go bad or the injector it's self is bad and causes a rich mixture.

 

Just a couple of things to try. Most EFI systems 80-89 are fairly similar. See if there are any other threads with people with the same problems. Even if it isn't a Z31, it will probably be relevant and/or help.

[Drax240z]

Catalytic converter plug typically leads to low power. Just remove it anyway and put in a test pipe if you can get away with it.

 

From what you are describing I wouldn't expect a cat to be the problem. Dan has some good advice.

[Careless]

Sounds like you are running way rich. Unplugging The O2 sensor wont help matters as it's probably narrowband. Sounds like your plugs are pretty fouled at this point too. I would start by checking your AFM and all it's connections. Also pull each plug and see what color they are. Soggy and black = rich. If it's more apparent in one cylinder, check injectors. Also try disconnecting your cold starting injector. Sometimes the temp switch for these go bad or the injector it's self is bad and causes a rich mixture.

 

Just a couple of things to try. Most EFI systems 80-89 are fairly similar. See if there are any other threads with people with the same problems. Even if it isn't a Z31, it will probably be relevant and/or help.

 

My theory behind removing the 02 sensor was to allow a bypass for stuck gasses.

However Dan, you are right on the money.

pulled the plugs today and they were really black and sooty. a little wet, but not too much.

 

I replaced the ECU at one point and my Fuel Pump circuit and Ignition Primary Circuit codes dissappeared, but the Coolant Head Temperature sensor remained... This struck me as odd, as I replaced the CHTS with an aftermarket version.

 

Tomorrow I will be ordering the CHTS and going to nissan on Tuesday to pick it up, and Hopefully the only remaining code will be the Fuel Temperature sensor which is new to me... but also irrelevant as I've been told. I figure since some are ditching the stock FPR and going with aftermarket ones that do not have the fuel temperature bung, it makes sense.

 

I might change my oil too, I think it's been fouled and mixed with excess fuel and it's now thinned out. Another 60-80 bucks + sensor cost down the drain, but I think this is the last of it! Should be running real nice when I get it going this time.

 

I have some new platinum Gpower NGK's as the store was surprisingly out of all other plug types. I think I can have her running well enough to get around again until I have to pull the intake next week to redo the rail, because I had an instance that almost caused an engine fire. Good thing I hand-made those Taylor 409 plug wires in time, or I would have been running on really ratty Honda Accord plug wires that would have sparked, no doubt, and caused an insane engine fire when #4 injector lower-hose decided to unseat itself from the umbrella hat clamp. I'll be removing the umbrella hat clamps in favour of proper fuel injection clamps this time around. It should be a lot better this way.

[WizardBlack]

Well, I don't know your car(s) well enough to know what vehicle you're talking about, but....

This sounds like an excessive rich/lean condition or a horribly mis-timed setup. Just make sure you get an affirmative identification on the problem before running it very long as-is. LUK.

[Careless]

Indeed. I'll be changing the CHTS and re-indexing the distributor. it seems as though my distributor is way out counter clockwise, and i can only get it a hair passed 15 BTDC, but I swear I set it properly at one point. I think the computer sees the CHTS as not installed (faulty aftermarket POS!) so it's knocking timing back and dumping fuel as a cold-start enrichment program.

 

It's an 87 300zx Turbo, by the way.

[dan5138]

Aww you live in canada, or I would steal your diff. I need one out of a 300zx like that. Let us know how it runs after changing timing / sensors.

[Careless]

It's ok, it was already "stolen" as far as I know, but I'm over it

 

I changed the sensor today, and put some platinum G-power plugs this time around as they only had 5 v-power and 4 coppers.

 

I left the gap at the 0.4 instead of gapping them to 0.44 as I didn't want to mess with the fragile platinum electrode tip... I think it will be ok. some Z31 guys running 0.39 gap, so I believe it to be well within operating gap range.

 

I replaced the CHTS using AZ Bum's method. Took literally 5 minutes.

 

I broke the sensor's connector using a big screwdriver and a 24oz hammer with 3 light taps. it literally cuts the connector off the sensor body. I then removed the thermistor and connector together, removed the sensor with the 19mm socket and a universal joint socket adapter (wrap those socket u-joints in 4 to 5 even layers lightly stretched electrical tape, and you can position them any way you want and they will stay that way when trying to align the socket onto a hex head... and it saves your finger's flesh from being caught in the u-joint from having to hold it where you want it!)

 

I then put a light twist of teflon tape around the sensor, knowing that the teflon acts as a slight lubricant and it also does get cut as it's being threaded in, so grounding is a non-issue. I tightened the sensor down with some lengthy pliers and a firm grip and twist, and it bottomed out and went for another 1/2 turn, carefully trying not to grab the sensor connector.

 

Put the sub-harness in and it fired up like a dream. It idles a lot better now and my timing mark on my balancer started to work it's way more and more towards the advanced direction (CW) so It allowed me to turn my distributor CCW in increments as the coolant temperature started to give the ECU feedback so it could make sense of the cold-start look-up table in the fuel-map and timing region on the ecu.

 

My distributor is now smack dab in the middle of it's swing-range, as I installed it way back, and it also lands squarely on the timing mark on the lower timing cover.

 

I think this is it, guys and gals.

 

I think my engine is finally running in tip top form. I still get the CHTS code, but I no longer get the Fuel Temperature Sensor code (fiddled with some wiring and some taping up of a few stray pre-injector-service campaign wires)...

 

I don't think the engine got up to full operating temperature to finally erase the code, but it definitely runs a heck of a lot better, and I bet I can pull out some timing just a hair more when it hits that point. The plugs seem to be doing their job well, and if it continues to run like this, the wires and plugs will never have to be changed for the next 3 or so years... only the cap and rotor if they go bunk!

 

All that's left is to re-do my injector hose clamps (because I almost had an engine fire), and put in my new FICD and IACV when they come in... but those are unneccessary to drive it for now... and then I need to install my 70 amp relays to replace the 40 amp controlling my fan and THAT IS ALL SHE WROTE.

 

Now where's that super cute girl to whom I promised ice-cream and t-tops a while back?

[Careless]

Damn. the miss is back!

I got the timing set now, put the exhaust back on, and after about 10 mins of driving the car starts to dump fuel and not ignite it, and the cat starts to pop-pop-pop and sometimes the car will lunge forward or sometimes it will continue to pop.

 

not too sure what the heck it is. codes still say CHTS, but I can't seem to clear the friggen thing. But the chts must be crossing tables for enrichment mode if the timing is back to where it should have been long ago, and the distributor orientation is not maxed out.

 

=(

 

i'm lost.

[WizardBlack]

Damn. the miss is back!

I got the timing set now, put the exhaust back on, and after about 10 mins of driving the car starts to dump fuel and not ignite it, and the cat starts to pop-pop-pop and sometimes the car will lunge forward or sometimes it will continue to pop.

 

not too sure what the heck it is. codes still say CHTS, but I can't seem to clear the friggen thing. But the chts must be crossing tables for enrichment mode if the timing is back to where it should have been long ago, and the distributor orientation is not maxed out.

 

=(

 

i'm lost.

Does it need 10 minutes to start doing it every time you start up from cold or did it run good for 10 minutes and now is running badly from the very start each time? Sounds like lifted circuitry, too.

[Careless]

Problem solved... errr found.

 

so i went to unplug the CHTS connector that I tested more than twice, and the yellow wire crumbled in my hands. so I rewired it in the dark with a power inverter, soldering iron, a connector from a burned down sentra we had at one point, and a headlight to see what i was doing. heat-shrunk it, and taped it, and loomed it.

 

problem was still there... took it for a spin... every 2 or 3 km it would start to bog like heeeeeelllll.

 

finally, I took the advice of two of my good car buddies (one of whom was shotgunnin') and unplugged my sort-of-new o2 sensor. They figured something had to be altering fuel tables. and I figured... I changed 2 of the 3 possible cross-reference signals for cold-start and fuel enrichment... why not!

 

I changed the CHTS and that helped my timing come back.

I changed the AFM twice, and that did nothing.

I unplugged the o2 sensor and the car is friggen ROCKET now.

I'm very impressed, mechanically, with the way everything is running. My car is burning off all sorts of carbon, and tomorrow before I head to my parent's house to visit them, I'll be sea-foaming the bastard in a nearby dimly lit parking lot, after work hours.

 

Tomorrow I shall order an OEM Nissan O2 sensor, and I'll get it on Tuesday because they close at 8:30 pm.

 

It struck me as weird, because I unplugged the o2 sensor when I was doing the CHTS diagnosis. during that time it did nothing. the O2 sensor must have been waiting for the CHTS to do something... So now that I fixed the CHTS wiring, the o2 was the only thing left, as I inspected the MAF wiring quickly before going for a drive... I did not test the wires, I only looked under the boot for corrosion, and I was surprised at the cleanliness of the harness connections. The TPS wires were way worse under the same style boot.

 

I also made slight modifications to the PCV system as per another thread here, and I will be buying a brass T fitting to put in the lines to allow venting of the can.

 

Thanks for all the replies. I'll report back if anything goes bonkers again with the new sensor. I guess all the idling I was doing when I had the assembly lube and the turbo pushing some weird substances out into the exhaust caused the sensor to soot up passed recoverability...

 

Maybe I can make it to BZF now.

[FlatBlack]

Maybe I can make it to BZF now.

 

Do it!! ^

 

My exhaust is crushed a bit under the car and I was hoping you would find your exhaust to be the problem, so that when I got a new header-back on mine it would help with the power some. Wishful thinking I suppose. Is that ricer-ish of me?

 

Glad to hear it's running well, see you in a couple of weeks

[Careless]

my exhaust has a small leak, but I'm really passed it at this point. i think it's under the heat shield, right infront of the catalytic converter... so I'm not going to bother. I'll be making or getting an exhaust soon anyways.

 

gotta see how the car goes for a bit before I make my decision to go to BZF.

[Careless]

ok, so i seafoamed the car today, and now it runs like a bag of ass.

it idles at 7k rpm, engine shakes a little bit, doesn't rev nice until something like 15-1800 rpm... and my exhaust leak is a little more apparent now.

 

it still burns oil too.

 

i'm pointing towards fel-pro valve seals or maybe the guides. I got 150psi on my compression test, which was done after the engine not starting for 2 weeks, so it was bone dry. I dunno what to think at this point. kinda pissed. I was supposed to take it up to my parent's place this weekend, but whatever. I'll have to get a ride.

[Careless]

im convinced something is wrong with my valve seals.

the car did not burn oil before i took the heads off, and now it's burning a ton of oil, and the only seal other than the headgasket that I changed which would separate oil from combustion could be the valve seals, as I'm getting 150psi on my compression tests, and my coolant is not burning as it's always full, anddddddddd... my oil is diminishing quickly.

 

I'm thinking the felpro intake seals for the VG30 that were in the 87-89 headgasket kit were a bad design... Why? because i ordered a back-up set before the weekend at the time when i did them, just incase i screwed one up, and i noticed the back-up set was quite a bit different than the ones that came in the Head Gasket kit, even though they were the same part number.

 

I'm going to pull the intake to put a new AAC and FICD on there, and pull the injectors to replace the hose with some better hoses and real clamps instead of umbrella hats... and then I'll just take off the rocker shafts and lifter plates and try at the seals again. I really think it's a seal that either popped off due to the different design or maybe I whacked it on a bit too hard because the intake seals don't have a positive lock, so it's tricky to know when they're on good. the exhaust ones just snap into place.

[Careless]

my only diagnosis at this point is that the valve seal was installed incorrectly (that's a first for me, I've done this countless times, but the difference in seal design may indicate something that I couldn't help here)... and the seafoam resulted in the burning away of the carbon on the valve stems that was there from initial valve stem leakage, and now it's allowing more oil to flow down the guide or be sucked in.

 

I did not check the clearance of stem to guide, but they would not move even the slightest when the valves were slipped into the guide, and there was no axial play at all.

 

I guess I'll just have to open her up.

[Careless]

I'm seriously considering another engine at this point.

 

I went to start it earlier and it knocks at low rpm, like 700rpm or so... and then depress the clutch pedal the idle goes up a touch to 800rpm and it idles fine, but with a slight engine shake.

 

I believe an oil control ring may be cracked or something in that area. I'm not pulling the heads to deal with this motor anymore. I need to get something else.