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Discussion Starter · #1 ·
OK, all you "Sherlocks", let's run this one down.........

95 Impala, 210K, PCMforless programming years ago.

July 2009: Plugs, plug wires, pcv valve.
August 2009: Motorvac
Sept 2009: Temp. sensor. AC Delco Opti. Fuel filter.
Feb 2010: Fuel pressure valve.
April 2010: New AC O2 sensors, fuel pump, fuel filter, IAC valve. Pressure after fuel pump install 40-42 psi. Held pressure for 30 min or longer after test.

Car was running just fine in July of last year. I replaced plugs and wires just for something to do. At the same time, I ran a bottle of fuel injector cleaner through the tank (but probably not diluted with as much gasoline as suggested on bottle).

I began noticing that after July, the car was idling like crap, accelerating even worse.
I took it to a shop in Canada and had them run diagnostic tests. Nothing showed out of range. They did a Motorvac, which seemed to cure the problem for a while.

September, problems back, and began having trouble starting if the car sat for any length of time. (I was working in Canada, so parts where either hard to find or extremely expensive and my tools were far away in Texas.) I replaced the Opti and the temp sensor. I also changed the fuel filter.

Ran OK with the exception of intermittent non-start issues. If it didn't fire right up, I would have to wait a couple of hours, grind on it and finally it would start. I replaced the fuel pressure valve next.

Got the car back to Texas in April of this year. Had issues with passing emission tests 2x with inspector sniffing DS tailpipe (no X pipe, etc, straight duals). Changed O2 sensors and changed the fuel pump since I could get one at a decent USA price. Had inspector test on the PS tailpipe. Passed emissions like a new car!!

Car was running fine. Put it in body shop for long overdue refreshing. Fast forward 2 months.

Moved from Dallas to Houston, no extreme weather change, just humid as a mother.

Car has started running like crap again. rough idle, poor acceleration from start and at speed. I notice that at a stop light, if I give it a little gas, the idle will smooth out.

Datamaster shows HIGH O2 readings on DS, but normal, very low readings on PS. Idle is around 550, fluctuating +/-, but fairly stable. No codes.

I'm thinking a rich condition on the driver's side.

I'm wondering if the catalytic converter may be clogged, but exhaust from tailpipes "feels" about the same. No red-hot glow from manifolds or converters.

Injectors "feel" like they are all firing, though I know that is not a true test.

I am thinking that I may have Motorvac done again, but that's $150 I could be wasting.

I could change the Cats (or at least DS). I found a link to Magna-flow cats in the "Exhaust" section below, so I can get them for a good deal. There again I could be wasting money that isn't really in my budget (OK, so it's not in my wife's budget, you know how it is...).

I am wondering if I may have gummed up the injectors when I ran that @!#$ through there last summer. Maybe a little Sea Foam would flush out the injectors? Couldn't hurt, only a few bucks.

OK, now it's your turn....Discuss.
 

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There again I could be wasting money that isn't really in my budget (OK, so it's not in my wife's budget, you know how it is...).
Sigh... I do know what that is like.


Its a long shot but do you have any after market gauges hooked up such as a air/fuel ratio meter? After I did my cam/head swap last summer my **** was running pig rich on the drivers bank only. Turned out that gauge was hooked up incorrectly to the o2 sensor and the person who was tuning my car cut the power to the gauge and the problem went away.

Like I said a long shot but it cant hurt to ask.
 

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Discussion Starter · #3 ·
No. thanks.
 

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Discussion Starter · #4 ·
Ran Sea Foam thru the brake booster line. Twice. Made a bit of difference in acceleration, but the problem of rough running and poor performance is still there. I noticed that as I was pouring in the Sea Foam, there was white smoke coming from the manifold/cat connection on the driver's side, but not the passenger side. Could that be an indication of a back up in the catalytic converter?

Any quick ideas on checking whether a catalytic converter is clogged up?

Thanks,

Clay
 

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I would think that that smoke would only really indicate that the connection point is leaking, you did see smoke coming on that side tail pipe right?

With the amount of mileage you may try throwing a set of injectors in it, factory versions, you can find them flow matched on Ebay usually cheap. I know it is a long shot, but worth a try as you could have an injector on that back that is sticking open.
 

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Discussion Starter · #6 ·
Oh yeah, smoked like mad, just as expected.

What size are our OEM injectors? 30lb?
 

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A leak at the manifold/cat connection can introduce fresh air into the exhaust causing the O2 sensor to think that bank is lean. PCM will add fuel to try and compensate.
This will show up as high BLM value on a scan tool.
Fix the leak.
 

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Discussion Starter · #8 ·
Dave,

Where in Ontario are you? I worked in Ottawa/Gatineau last year and spent a little time in Toronto as well. Beautiful country, mostly nice people.
 

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If the "idle" smooths out when on the gas a little at a stoplight, then we have a "gas speed problem" Don't take that to mean a fuel problem. Think of how fast the exhaust gas flows through the piping. It flows much faster when there is more heat and available and also is less influenced by the "leak" in the exhaust than at idle, but enough of an issue to "Drive" the fuel trim rich on that side to correct for the percieved extra amount of oxygen present in that sides exhaust.

Survey SAYS!!!:


Cracked manifold or broken/missing/loose bolt.

Remember first rule of troubleshooting COMPREHENSIVE VISUAL INSPECTION!!! Rule those things out and get back to us.

Chris.
 

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Discussion Starter · #11 · (Edited)
Whistle past the graveyard

I checked the manifold bots this weekend and discovered the front and rear bolts on the driver's side were loose. Cranked them down and I **think** I may have found the problem. It sure ran better this morning. Thanks for the tip, Chris.

Of course, I had to replace my starter this weekend (never saw one where the "ear" that holds it to the engine was broken, but there it was.) so the money I may have saved on Catalytic converters went into the starter.

It's always somethin'.
 
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