Hey all,
Not a good night. Motor started sputtering when reaching 3000 rpm. Half-way though a tank of gas. Idles fine. No odd noises. Sputters under acceleration and in park.
Google has not been any help.
Thoughts?
Any help would be greatly appreciated.

When was the last time the air and fuel filter and injectors/wires were changed? Another thing to check would be the distributor cap. Engines need fuel, air, and spark and it's not getting enough of one or the other. Being it just out of the blue started it's something simple.

Just picked up the broken Celi from the dealer. $120 for a diag.

As I understand it, turns out a bad O2 sensor (been bad for awhile) was causing the motor to run too rich (I was only getting 20 mpg) and the unburned gasses melted the Catalytic Converters. Too much exhaust attempting to go through the confines of the melted converter is causing the sputter. That is the story from my local Toyota dealer. From what I have read this is common.

Cost for 3.5 hours (!) labor, the exhaust manifold w/ front converter, rear converter, 2 sensors and 4 gaskets? $1500 installed. Wha-wha-what?!

As a reference, the cost of parts from Advance? $500. These are for direct fit parts, not universal.

I have a high-end muscle-car co-worker whose son is a mechanic at a local dealer as may be interested in looking at it.

Looks like these are bolt-on parts. Can anyone confirm?

If you live where they don't do emissions just remove the cats and scrap the old ones. Will get a check engine light since the rear O2 will get getting straight exhaust. Of course if you have emissions you'll have no choice but to. It'll be cheaper getting the cats from RockAuto or eBay though.

use a spark plug anti fouler on the rear O2 and it wont throw a CEL

Update:
The dealer swore up and down it was melted cats. Wanted $1500 to fix. Complete written estimate of everything. Bought the 2 Cats and O2 sensors from RockAuto and had a reputable garage do the install, $650 total. Check engine light off! Problem solved?

No.

Pulling out of the garage, I gunned it. Hit 3800. Sputter back to 3000, Up to 3600. Back to 3000. Hit 4000 and took right off! Runs great above 4000. So the problem is engine stalling at around 3800. Backfires as well. Before and after that, the motor is great. Check engine light back on.

I have read ALOT of possibilities, like various ignition, computer, and fuel issues. With those, I could see hitting a wall at 3800 and running like crap above, if it would go above at all. But to have issue at that particular range perplexes me (actually I am extremely angry that I have thrown away $650). I sold alot of vintage video game systems to pay the $650.

The garage is looking at it now. It threw out several codes. The guy feels bad that he did not check the computer first, but we took the dealer's word for it. There is usually a 3-5 day wait for the garage, but they are looking at it as I type this.

I will post the results. I've got a bad feeling about this...

You may not need to replace the cat, it can probably be refurbished in this case.

You will need to remove it first. Unbolt the bottom of the converter from the mid pipe at the front of the engine compartment. To seperate the cat from the manifold(3 bolts, 2 nuts) you will probably need to first unbolt the entire assembly from the engine (manifold and cat). Once out of the car the rear bolts on the cat will be easier to access.

Once you have removed the cat, the upper side will be exposed, and most likely be clogged solid. Use a handheld grinder to remove the top fractions of an inch of catalyst honeycomb until the passages are cleared and no longer blocked. Now rinse it out well with water or compressed air to get out all the junk left over from grinding which fell into the honeycomb passeges. Bolt it all back together and enjoy the $500 you just saved yourself. Try not to breathe in the dust created from grinding, there are some heavy metals present in the catalyst which may be harmful to your health.

You just need to replace the plugs, cap, rotor and wires to fix this type of issue. I'm not sure what type of crack the dealer is/was smoking.

Yea that's what my dizzy did would it was going bad. Def seems like an ignition issue and nothing exhaust related.

Check the primary and secondary resistance on the coil. If it passes that, test the fuel pressure (you can rent a tester at AZ or OReilly). Those would be the two most likely culprits but the coil is by far the most likely critical component to fail on 6gc's at this time in their lives based upon what I've seen on the forums.

You can also check the wires either by checking resistance with a multimeter or by wiggling them around and watching for blue sparks when it is very dark at night. Replace the plugs, they are only $2 a piece and need replacing at least every 40,000miles if they are copper, half that distance would be prudent; I wouldnt trust platinums to last the sales pitched 100k miles in a 20year old vehicle either.

Cap and rotor can be visually inspected for pitting on the points or a crack in the cap.

So what was it?

Frayed wire at the crankshaft sensor. Three strands of copper holding it together. Would have been stranded when it completely gave way. It did not like the hard acceleration. Very, very weird.

New wire. Runs great! $85 installed.

Wasted $650 on converters that I did not need.

My lesson learned... get a second opinion.

Well, the issue has returned...

When the crankshaft wire was replaced, there were two EGR codes as well, but were ignored per advice from the garage. The garage changed the wire and the car has ran great for a month. My millage has steadily rose from 20 to 26 mpg (same driving-very strange!). Now it is sputtering again. The garage checked and the wire looks fine. They also checked and there are the same two codes for EGR issues (I did not write them down). Could it be the EGR system?

Thanks!

99% of the time when you throw EGR codes, its the VSV mounted on the back of the block.

Amateur fix? Guessing not.

Vacuum switching valve, not hard at all. That or it could be the EGR modulator. There are procedures for testing all of the EGR components and finding which ones are at fault.

I've done some further digging and found instructions on removing and cleaning the EGR valve of deposits. Checking the other components as well. Weekend project.

Thanks!

Another thing is the EGR temp sensor is probably caked in carbon, so give it a clean while you're at it. One thing is be careful on what you clean the EGR valve and modulator out with, the rubber membranes don't like things like carb cleaner so they're probably better off in hot water with Dawn.

This post has been edited by Box: Jun 25, 2014 - 4:38 PM

The check engine light came back on. Advance checked it. Showing P0401 and P0441. From the P0401 the EGR valve is clogged, causing insufficient flow. The weather is supposed to be crappy this weekend, so I know what I will be doing. Thanks for all the suggestions!!!

Insufficient flow means the EGR isnt opening, you will experience increased performance and higher NO2 emissions in this case. It is not the cause of your misfire.

Check the cap, rotor and coil. Check the fuel pressure. Make sure the crank position sensor connector is clean and devoid of oil, oil can get into the wire connector and make an intermittent bad connection.

This post has been edited by Special_Edy: Jun 27, 2014 - 11:07 AM

Not Bosch Platinum spark plugs are they?
I second checking the cap and rotor and checking or just replacing the plugs.

NGK and Denso are my plugs of choice.