passed smog, but still loping.

mxhooptie · Post by **mxhooptie** » July 7th, 2007, 3:01 pm

hello, first post here. this will be long, please bear with me. i want to be as detailed as i can.

i first consulted this forum about smog/emission issue. i tried almost
all the tips that i read here; tune-up, oil change, spark plugs, air filter, fuel filter, PCV,
O2--even though its not out yet.
i didn't change the wires because they look new. i didn't change the cat cause
it still works; and its expensive to replace. i tried acetone and then, the Coleman fuel trick, even voodoo.
checked codes, there were none. still, the car failed emissions test.

on my third test:
@ 15 mph (1740 rpm) > HC is 8 PPM above max
@ 25 mph (2839 rpm) > HC is 15 PPM above max
CO and NOX are both well within limits.

the smog tech pointed out that my car is "loping". new term for me

but i'm sure not for most of you. i thought it was just the car acting its age, 177540 miles old.
he blamed the loping on poor combustion, misfires caused by "a bad valve" and
my bosch plat 4's plugs, which, in his own words, are "sh*t".

what do yo guys think?

can loping be caused by a vacuum leak as well?

can i get rid of the lope simply by replacing the bosch with ngk and a new wire set?

please, i need your expertise. she's a daily driver, my work pony. i have no dreams or aspirations
for this car other than making it pass smog and running it for 100000 miles more.

thanks

Tunes67 · Post by **Tunes67** » July 7th, 2007, 7:17 pm

First off.. he is 100% right about those bosch plugs.. they are crap. As for the bad valve.. he could be right about that as well.. especially considering the mileage on the engine. The way to test for it without spending a lot of cash is to go buy a compression tester. They cost anywhere from $15 to $50 depending on the quality of the unit you get. You dont need the best one out there.. a cheapy will tell you what you need to know even if the results arent the most accurate.

Now.. since you will be replacing those bosch plugs.. start by taking out all the spark plugs. Then unplug the wiring harness connectors to the distributor.. then screw in the compression tester into the first spark plug hole. Now have a buddy crank the engine over while you watch the needle on the compression tester.. when the needle stops moving up.. stop cranking the engine.. record the number and move to the next cylinder. Once you have done all 4.. put in your new spark plugs (I recommend NGK) and plug the distributor wiring harness back in. Then come back here and post your findings.

Tunes67

Tunes67 · Post by **Tunes67** » July 7th, 2007, 7:28 pm

I'd like to add that even if you find valve train problems.. its not the end of the world and that there are relatively inexpensive solutions IF you are willing to do the work yourself. You dont mention where you are from or how strict your emissions testing is in your area.. in Washington state there is a limit on how much you have to spend to get your car to pass emissions.. I think its $100 or $150 and you can then get your license tabs even if you failed emissions.. might want to check and make sure there isnt a similar law in place in your area.

I will also add that a old catalytic converter CAN cause you to fail your emissions in the manner that you have done so. Just so you know.. HC = Hydro Carbons.. and thats a fancy term for too much burned oil residue in your exhaust. A catalytic converter that is no longer doing its job right wont be burning off that excess oil as it should. Why is there oil there to begin with? Cause you have 177k miles and you probably have oil getting past the rings or valve seals. This is common as engines age. As a double whammy.. the more oil residue in your exhaust, the faster your catalytic converter will go bad. Now the good news.. even in bad conditions catalytic converters will usually go 100k miles. So if your compression test turns out ok.. its likely to be replacing the catalytic converter as the next step. The bad news is.. that loping is probably being caused by a burned valve.. but the compression test will reveal that if that is indeed the case.

Tunes67

Typhoonk · Post by **Typhoonk** » July 7th, 2007, 10:58 pm

loping eh?

do you have a 1992-93 engine SOHC or a 1994+ DOCH 4cycl? manual, auto?

some suggestions
1. CHANGE THOSE DARN PLUGS!! use NGK they are pretty cheap
2. Replace your PCV valve and tube (thing gunks up like no tomorrow and is cheap to get new)
3. Replace Fuel filter - easy to replace, check online manual for hints
4. Run fuel cleaner or similiar ever so often in a full tank of gas
5. Take apart and clean out your intake, and Idle air control valve
6. Get some electronics cleaner and clean MAF/VAF connector, IAC connector, and any other connector you hands can get on.

If all this and what you've already done - and you idle still 'lops', you can test your throttle position sensor (POT's do where out-lol pot

), and your maf/vaf for proper values (also check the online manual).

Good luck!!!

mxhooptie · Post by **mxhooptie** » July 8th, 2007, 2:39 am

i left a lot of things out. sorry. please, bear with me again.

the car is a '95 1.6L DOHC, manual, with 177540 miles.
i don't want to say what state/region i'm from, if that's OK,
for it might affect your judgement.

background info:
it sat for 2 years with little to no operation before i bought it. i bought it really cheap,
so the the previous owner has pretty much washed his hands off it. and please let's not get into that.
it's my problem now

the loping:
at cold starts in the morning, it idles fine. as it warms up, the loping begins and the car shakes.

the car accelerates smoothly. once it's in motion, there seem to be no issues.
doesn't buck, doesn't hesitate, doesn't back fire. it hums like a dream machine.
it's hard for me, or anyone who has riden in it, to believe that the car has problems.

but once it comes to a stop, the loping returns. the muffler sputters too.

weird:
while at idle, the loping stops when i turn on the AC.
(and no, the smog tech won't let me leave it on during the test.)

sometimes, the car does NOT lope when at a stop. but it lopes again once i put electrical load on the car.
example: when i turn on the headlights and then, pump the brakes,
which turns on the brake lights, the car lopes again.
also, i noticed the lighting in the instrument panel dims
every time i step on the brake.

related?

i appreciate every input so far. thank you.

P. S. i thought HC was due to unburnt fuel. i replaced the bosch's with NGK g-power... no luck, still loping.

SuperK · Post by **SuperK** » July 8th, 2007, 7:52 am

good god, I feel like I'm talking to my roommate.

He bought a MX-3 with 175K miles and it loped bad.

We did a standard tune up and of course it still loped, but we also replaced the intake. Since we both have MX-3's and I had already put in CAI in mine, I gave him my old intake equipment. Seemed to work wonders.
You might inspect the car for any vacuum leaks that might hinder your idle.

I would also recommend replacing your CAT. I replaced mine and noticed a tremendous difference just in the smell of exhaust. Now it smells like roses! (Not really...)

If you want to check real quick like and see if you might need to change your Cat, if you look around the heat shield on the Cat, and if there is any black soot/residue, then your cat is leaking. And it's more than likely dead.

You can buy a Magnaflow replacement cat for 60 bucks and have it installed for another 60.

And I also tried the Bosch 4+ platinum plugs. Worst mistake ever. Went with NGK platinums, then got ever so curious and tried their irridium lineup.

Typhoonk · Post by **Typhoonk** » July 8th, 2007, 3:47 pm

if you want to just pass the emiss test - then just adjust your TPS and idle so you get more/or less fuel just so you can pass the test

I think if you rotate the TPS one way it increases fuel (goes rich) and if it goes the other way it will lean out. This should help one test on the emiss test. (adjust ever so slowly!!!!) might want to borrow a air/fuel meter.

Then adjust your idle (search on this site to find it), so it chills at about 800rpm. Should be within spec to pass the test - doesn't seem like your far off.

and if your car's rpm is jumping up and down at idle and this is messing up stuff or is just plain annoying. You can disable the day time running lights - as this unit seems to heat up and suck up a lot of power!!!! and all you have to do is unplug a relay!!! it's in the passenger kick panel and it's the one towards the front of the car. Just unplug, and your DRL's should not come on.

Typhoonk · Post by **Typhoonk** » July 8th, 2007, 3:51 pm

just look it up and it sounds like (with your results) that you are running to lean!!! you need more gas man!!!!!

1. Fuel filter
2. Adjust TPS to within specs

Typhoonk · Post by **Typhoonk** » July 8th, 2007, 3:52 pm

yes I am doing nothing today. pass the beer!!!

mxhooptie · Post by **mxhooptie** » July 8th, 2007, 11:46 pm

SuperK wrote: We did a standard tune up and of course it still loped, but we also replaced the intake... I gave him my old intake equipment. Seemed to work wonders...

You might inspect the car for any vacuum leaks that might hinder your idle.

so, your friend, did he have emissions issues as well? did the intake replacement fix the loping?

if i do find a vacuum leak, then what?

thanks

Typhoonk wrote:I think if you rotate the TPS one way it increases fuel (goes rich) and if it goes the other way it will lean out. This should help one test on the emiss test. (adjust ever so slowly!!!!) might want to borrow a air/fuel meter...

and if your car's rpm is jumping up and down at idle and this is messing up stuff or is just plain annoying. You can disable the day time running lights - as this unit seems to heat up and suck up a lot of power!!!! and all you have to do is unplug a relay!!!

which way do i turn to lean it out?

way ahead of you on the the daytime running lights. although, my idle isn't bouncing.

also, what happens if i do the e-test with GROUND and +TEN pin jumped? the loping seems to stop in diagnostics mode.

thanks

SuperK · Post by **SuperK** » July 9th, 2007, 6:23 am

if you do find a vacuum leak, which commonly occurs in the "accordian tube" from the throttle body to the MAF, you can prolly DUCT TAPE it, although I'd suggest just replumbing the whole system.

While you could get a cheap replacement from a member here, all those tubings are going to be old. I'd just get the eBay Special Cold Air set for 50 bucks. The aluminum tubing will solve all your cracked tube issues.

Apparently he did pass the emmisions test just last week. To be honest, I don't see how that was possible, as his car was smoke screening a month ealier like you wouldn't believe, and numerous exhaust leaks on his down pipe.
I guess Tennessee's e-testings are very slack!

mxhooptie · Post by **mxhooptie** » July 9th, 2007, 12:15 pm

SuperK wrote:if you do find a vacuum leak, which commonly occurs in the "accordian tube" from the throttle body to the MAF...

ok, the accordian tube does have tiny cracks. i've looked and felt the inside of it, the cracks doesn't go through all the way in, it's seems to be on the external surface only. i don't feel air around it when the engine is running.

mxhooptie · Post by **mxhooptie** » July 11th, 2007, 3:34 am

i just did a compression test. here are the values:

150 165 160 170

so what does this mean?

SuperK · Post by **SuperK** » July 11th, 2007, 8:48 am

those numbers look pretty good to me?
for a high milage car...

Tunes67 · Post by **Tunes67** » July 11th, 2007, 10:41 am

They are indeed exceptionally high (much higher than I expected) and that indicates that the valve train is in decent condition. This in turn means you can rule out the burnt valve possibility that was mentioned earlier. If you had a burnt valve on one of the cylinders you would come back with one (or more if there were multiple burnt valves) compression figure way less than the others. For example.. 150 165 60 170 Indicating that cylinder #3 wasnt sealing properly and not building correct compression.

Just for a point of reference.. stock compression is only 180.

The loping is only at idle correct? Under acceleration the power is smooth and consistent? I would also suspect a vacuum leak at this point. One other thing.. does the loping seem to happen more frequently when the engine is cold, warmed up or does that not seem to matter?

Tunes67