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2002 Hyundai Santa Fe AWD 2.7Lt Engine, 90K miles Causal Analysis

Codes: P0302, P0304, P0306, and P0300 Obviously related to Bank 2 or front side cylinders. Verified or replaced knocks, all O2’s, crankshaft, and camshaft sensors, ignition coil assembly, cables, and installed new iridium spark plugs. All done in addition to the timing belt kit installation (T-belt, water pump, tensor and idler pulleys, tensioner) part of a near to 100K miles preventive maintenance. Also replaced many hardened and deteriorated hoses. In this particular vehicle almost all old sensors plastic connectors degraded to the point of crumbling while handling them. The crankshaft sensor wiring insulation was almost gone thus shorting the device. After several runs in few days the check engine gave the stated codes and the following freeze frames data:
Fuel Sys1 = CL
Fuel Sys2 = CL
Load_PCT(%) = 29
ETC(F) = 93
Short FT1(%) = -2.3
Long FT1(%) = 1.6
Short FT2(5) = 0.8
Long FT2(5) = 5.5
RPM ( /min) = 1268
VSS (mph) = 0
The car have a slightly rough idling while in drive with the brake pedal pressed. Are there any ideas about what may be causing the trouble codes?

How does the exhaust stream feel if you let it pulse (as it comes out the exhaust pipe, at idle) against the back of your hand? Is it a steady “put,put,put” sort of feel? Or is it irregular? Another test is to hold a dollar bill and let it slip into the exhaust stream as it comes out the tailpipe. Does the dollar bill ever move toward the tail pipe?

What those tests are diagnosing? What component should be repair or replaced? Thanks for your attention.

DId this problem surface before or after the timing belt replacement?



Since this problem started after the timing belt job, there are 2 possibilities


Or the timing belt job got botched. If you’re off by a tooth or more, you’re going to have some problems.

Tomorrow I’ll verify the fuel pressure regulator at the bench. If good I will next go thru the drill of getting to the timing belt installation and while there verify all other components and torques. Thanks, I think I’ve covered all the bases since the least expensive.

To be honest it sounds like you replaced an awful lot of stuff at once. The codes should give you some insight as to the issues but you haven’t listed what they signify. To be honest I’d start off with looking at the ignition system at first since you replaced most of it. The part about crumbling connectors is disconcerting too. I’ve rarely seen that on a vehicle unless they’ve been exposed to extreme heat. Rough idle with the brake pedal depressed suggests a possible issue with vacuum lines.

The codes are for cylinders 2, 4 and 6 misfire, and the P0300 Random/multiple cylinder misfires detected. Fuel pressure regulator verified good. Vacuum lines Ok. Now is time to go verify the timing kit job. I’m recording everything. If there is a flaw I will request reimbursement, charge them back for a lousy job but I will not let them touch my car ever. If you are disconcerted by crumbling connectors you haven’t own a Ford vehicle like my 1993 Ford Aerostar. Ford and many other infected manufacturers uses their engineering talent to design for calculated failure of parts. They bet you won’t keep the car that long, but if you do they will keep milking the cow selling parts. Those above the curve like Toyota tends to be more liked for longer time trouble free performance.

Misfires will usually result in a change in the behavior of the exhaust stream. From a steady put-put-put, to an irregular pattern. If a serious timing or valve problem develops, then at times in the exhaust stream pattern, the exhaust will actually, by an undesirable suction effect, move air in the opposite direction, back towards the engine. If it is happening, it can be observed with the dollar bill test. An experience mechanic would be able to tell just by listening. Your computer is telling you that it is detecting misfires, but it is worthwhile to determine how serious it is. Some misfires are worse than others. That’s the motivation for doing this simple test.

What part of the country or world are you in? I ask because I have a 25 year old car with 285k miles on it and a 21 year old car with 366k miles on it. Neither has crumbling wire harness connectors or rotting insulation. And I’ve had to disconnect sensors and such many times during various repairs.


Ever work on older Benzes from the 80s up through the mid 90s?

Those were notorious for crumbling insulation and connectors

On every engine repair, we had to warn the customer that the wiring harness might not make it

@db4690, we called those “biodegradable wiring.” Just the fact of being meant that the wiring was deteriorating.

I think customers who used the dealer for service didn’t mind it much. They knew the cost of ownership and just chalked it up as a regular expense.

But the guys out there who buy a 10 year old Benz to impress everyone and then try to save bucks on service, well, just try and tell him he may need a $600 wiring harness after I replace 6 spark plugs and see how he reacts.


You are obviously very familiar with the 104 engine wiring harness

I clearly remember with a misfire, which was obviously attributable to the wiring harness

I gave an estimate to replace the harness

The service manager, who thought he was a genius, told a different mechanic to repair the harness

I watched the other guy attempt his repair, and let’s just say the harness was so far gone, he never had a chance.

In the end, that other guy wound up replacing the harness, at which point the engine once again performed flawlessly

And there were hard feelings all around

Should it be assumed the mechanic who was told to repair the harness got shortchanged a bit on labor… :slight_smile:

SAABs also suffered the degraded harness problem; including one of the SAABs I used to own.
Like anyone could repair powdered insulation.

What was it with that insulation? Was it a different material, something new from the factory, what?

For those reading this that don’t know what it’s like, just touching a harness to unplug a simple connector would cause the insulation to crack and fall apart for several inches. And trying to repair that stretch would cause the next several inches to shred to pieces. It was like watching a window shatter in slow motion. And the cure was literally to replace the engine compartment wiring harness.


I believe the service manager gave the mechanic that attempted the harness repair some grief

The service manager thought I was incompetent when I said I couldn’t repair the wiring harness. Even though I was right about that unrepairable harness, nobody ever told me that.
They told me I wasn’t clear enough when I said the harness couldn’t be repaired.

Perhaps Saab and Benz used the same supplier for the wiring harnesses . . .


They probably did use the same supplier and I completely understand why those harnesses are not repairable.
It’s impossible to fix something that is turning to talcum powder in your hands as it’s touched.

Slit the protective harness sheaths open on a SAAB and all that would be seen are crumbling wires bleached white with black copper showing.

@db4690, I only worked on 2 MBs, and regretted the job both times. Whenever one tries to roll in, I refer them to a specialist. I am surprised if Hyundai repeated the same mistake. I have actually gained respect for them over the last 10 years, being impressed with their latest line of cars, especially the Genesis. I’ll definitely keep an eye out for them if this is a systemic problem.