medic4life

Ok maybe this has been discussed before or maybe it is just a new one. I have a 04 with over 100,000 (yes over 100,000 on original motor ) I have a K & N intake on it. My problem is that after the car warms up it runs like crap. It idles rough, has hesitation, and don’t laugh but has a “valve knocking” sound higher in the rpms. It also becomes hard to start with longer cranking time need before it starts, after driving it. When it is cold it starts great and runs like a bat out of hell with no problems. I replaced just my plugs not to long ago maybe 15,000 at the most, everything else is original.

On a separate note one other problem I am having is under acceleration or going up hill (on warmer days) the temp spikes up. I have replaced all my cooling system including the radiator and the problem is still there not just as bad. Both fans work great.

Any help and recommendations would be great…. A Pre-emptive thank you for everyone’s help.

bse50

How's your compression? Fuel pump? Coils? Catalyzer?

Where are you in Az? BHR is near Phoenix and you may want to contact them

jmc23200

1) Valve Knocking? Knocking could be from shitty gas or mistimed combustion from poor coils
2) Make sure to use 93 Octane gas. Try a different gas station then the last one you went to when you need to fill up. If it is still knocking, replace your coils.
3) Don't drive your car like a bat out of hell when it is cold. This will damage your engine especially since it has high miles.

tubingchamp

iTrader: (3)

Fuel pump I would doubt, seeing as how it dumps MORE fuel into the engine while it's cold, it should run better warm in most cases.

Catalytic converter maybe worth checking out though... Have you removed yours OP?

If your catalytic converter checks out and there's no damage to the honeycomb and no rattling, get a compression check.

jmc23200

Don't waste your money on a compression check, you are over 100k miles which means no warranty. Here are the results of a compression check for you in advance.

Result 1: Your compression is ok. You pay $200 for labor.
Result 2: Your compression is low. Dealership tells you it will cost $5000 to replace the engine. You say that is ridiculous and pay $200 for labor and leave very unhappy.

Check your cat and perform a complete tuneup(coils, plugs, wires and seafoam the engine). You will spend about $200 -$300 on parts doing this yourself. If you are going to waste $200 on a compression check that wont really help you either way, you might as well spend it doing something that needs to be done anyway.

bse50

Actually the fuel pump, when worn, causes problem when hot
What if he spends the money to buy those parts only to discover, later, that he still needs a compression test? He might end up spending the same amount of money anyway and a serious approach is to avoid changing parts before knowing where the issue is. I agree that the coils are probably shot and all but changing them first would only add to the total downtime if the engine is gone.
On the other side if you have to change the engine putting on the new needed parts will not let you miss the car a single day longer.

jmc23200

Why would he get a compression test? What is the benefit once over 100k miles?

Fact: He will spend $200 on a test that will not benefit him. If compression is fine, he pays $200. If compression is low, he pays $200.

Fact: It will cost him $200 for new coils and plugs and a can of seafoam. If a tuneup and an engine cleaning don't solve the issues he is having, it's pretty safe to say he has low compression due to his mileage.

bse50

What if he then discover that it is a fuel pump issue and just changed the engine then?
I'm pretty sure that it should be a combination of poor compression and badly maintained engine but you can't make a diagnosis without the proper tools. A compression test in this case is the way to go to ensure that it is not his engine.
Considering the cost of a rebuilt engine (around 2700$+core return from Mazmart.com if i'm not mistaken) those extra 200$ would be well spent anyway.
And by the way isn't 200$ a bit too much for a so easy procedure?

jmc23200

Apparently you have never asked the dealer to do a compression check. 2 hours of labor at $99 an hour is what they charge.

Furthermore, a compression check is not really beneficial for him. It is a waste of money no matter what the outcome is.

bse50

I paid 60€ the last time i asked them to do one. Now i do them at home

jmc23200

You have a rotary compression tool?

A compression check takes 5 minutes and cost you $200 in the US. $100 if you can convince them to do it for the diagnostic price, doesnt happen too often.

bse50

100$ seems more in line for what we pay.
Yes, i do have a compression tool now because i sometimes work on rotaries

jmc23200

Well, I'm glad you get a cheaper diag price then we do in the US. The OP would still need to pay $200 for a compression check. He can always perform the poor mans compression check. Besides, the zoom zoom engine cleaning is known to help restore compression on carbed engines. 100k miles, I bet there be some carbon.

tubingchamp

iTrader: (3)

Thanks!!

Didn't know that.

Grazie!

bse50

Doing a compression test after some decarbing would be ok too, the only part that i didn't like was the one about changing parts before determining the eventual issue. He would have to change the parts you mentioned anyway but thinking that it will solve the issue while it may not could make you angry Prego

jmc23200

A fuel pump causes problems when the Fuel pump gets hot, not when the car warms up. A little bit of a difference. Fuel in your tank should be pretty cool

jmc23200

Hence me saying to replace the coils and wires first. If they are indeed the originals, that is a major problem.

Razz1

Sounds like you need a new engine.

Check the TB. Under there is tube that needs to be capped. Also, it can't leak.

Knocking sounds like broken Apex seal.

medic4life

Thank you all for your responses. Just to add more information... my plug wires and coils are still the originals, along with the cat. I was leaning toward it possibly being the cat before I posted this discussion. I also had the coils in the back of my mind. But, with the coils... I thought coils either works or doesn’t work. Is there a in between?

As far as compression goes can you use a regular compression gauge like you would for a v8. Can you do this by only pulling the lead plug? If so what should the compression be at? Or if the compression gauge would not give you a true reading on a rotary, can you compare the numbers between chambers to each other?

bse50

There's an " in between" for the coils, yes
It is fundamental to have a proper compression gauge that reads the rpm as well, and makes separate readings for each "chamber"!

RIWWP

iTrader: (2)

I just posted this in another thread. Maybe I should make a Coil detail sticky. The official pass/fail for coils is connection vs not, however from what I have seen and tested on my own coils, you start to get problems with them when the resistance begins climbing, well before they actually stop working.





Quote:
He is probably referring to the coils, but again, doesn't know enough to really know what he is talking about. Coil testing, even by a dealer, doesn't tell you anything. The proper test for coils involves removing them and testing them with a multi-meter for resistance. An official dealer test will 'pass' any coil that has any connection where it needs it, and no connection where it doesn't. However, the resistance that the coil has will increase over time, and this is where they degrade.

For example, I recently replaced my coils, and tested all 12 of the coils that have ever been on my car (2 previous sets + the brand new set), and technically all of them were 'within spec' from a dealer's perspective. However the first set causes misfires all over the place, the 2nd set was starting to, but it fouled my cat before it got too much worse. The 3rd set is brand new. Notice how the resistance values increase for each set based on miles?

I set my digital multimeter to Ohms, and on the buzzer. The test guidelines dictate that
- between terminals A and B, there should not be 0 or infinity
- between terminals B and C, there should not be 0 or infinity
- between terminals A and C there should not be continuity, 0 to several kilohm.

~35,000 miles on them before getting a few misfires up high, no noticable power loss, replaced coils and misfires disappeared. Unknown order in the 8.
Coil #1: 800, 558, 645
Coil #2: 806, 557, 640
Coil #3: 814, 556, 647
Coil #4: 806, 555, 645
Remarkably identical in values across all 4, especially compared with the 2 other sets.

Removed set, ~16,000 miles, I don't know which one was in which spot on the 8. I should have marked them.
Numbers are A to B, B to C, A to C
Coil #1: 804, 536, 608
Coil #2: 805, 540, 629
Coil #3: 770, 542, 620
Coil #4: 805, 544, 622

Installed set, brand new, 10 miles on them, numbered from front to rear in installation position:
Coil #1: 712, 477, 561
Coil #2: 768, 482, 577
Coil #3: 723, 490, 566
Coil #4: 713, 497, 572



The brand new set has the absolute lowest values of any of the sets, and since it's Ohms, which is resistance if I am remembering correctly, then they have the lowest resistance, the original factory 35k set has the highest resistance, and the 16k set has slightly lower resistance than the 35k set.

Coil #2 on the brand new set has the highest resistance values of the 4 brand new ones, but still better than any of the other coils, so nothing better that I can swap it to.



The dealer will keep saying 'coils are good' until one of them fails completely and stops providing a spark at all to the spark plugs, at which point your car will be hardly drivable, sputtering, chugging, no power, unstable spin on the engine, etc... Potential for heavy engine damage at that point, depending on which coil failed.

jmc23200

Looks like me saying to change the coils, spark plugs, and wires was right on the money now that we know that they are the originals.

jonny117

My 04' has just under 50k and I just replaced the plugs, wires, and coils (all were stock). It helped rather a lot but it still idles rough once it's completely warmed up just not as bad. Also it still takes several seconds, sometimes 10 or more secs to start when warm. Gonna try revving my engine to 3k before killing it and seeing if that helps, not sure why it would seeing how my engine should be hot enough to burn any left over fuel. I plan on selling it this spring sometime so don't really wanna put more $$ into it. Been a while since I've used seafoam, probably next on the list since it's cheapest and overdue. Is there an average mileage for the cat to go bad? and how much do they typically run if bad? $100, $200... $400?

RIWWP

iTrader: (2)

If you are within 80,000 miles, the cat is covered under federally mandated warranty. Just get the dealer to replace it without trying to tack on other unrelated charges. I am at a dealer right now while they replace mine, 53,000 on the odo.

If you are out of warranty, just the cat itself is $1,400 and change brand new. Lots of expensive metals inside the cat. It's far cheaper to get the most expensive midpipe out there (~$500) plus an AP (~$500) to block the CEL caused by no cat. If you go cheapest midpipe and ignore the CEL, you can do about $150 I think.

No legitimate business will ever sell you a used cat, however used cats are often up for sale on the boards here for $100 to $300 range from people putting a midpipe in and don't care to keep the cat laying around for emissions inspections.

jonny117

hmm, so they'll replace the cat free of charge if it's bad and im under 80k? May have to take it into the dealer and have em check it out, and if it's good then do a compression check.