Spark Plug Coils

[wang]

1999 Boxster, 30300 miles, tipronic trans

Does anyone have any advice or required replacement info for spark plug coils?

I have read many posts regarding spark plugs - but very little on coil replacement.

Years? Mileage? A local mechanic quoted two hours labor for changing the plugs at

US $90 an hour. He opened his mouth and made two mistakes. "You should replace the

coils." He then asked, "How many miles on the car?" I told him. He then said, "You don't

have to change the plugs until 60,000 miles. Nice price, nice guy - wrong answers.

Thanks for your help

Bob

[Loren]

Look for cracked coils or bad corrosion.

They can be tested as follows:

Check the resistance across pins 1 and 15 (black wire and green wire w/stripe -- not brown).

Resistance should be 0.3 to 0.7 ohms at 20 degrees C.

If they all look badly corroded I would replace them all. But if most look and test good - I would just replace any that test bad.

[PTEC]

The service interval on the plugs on a 99 is actually 30k. Its only 60k on the 2001 and newer cars. And as Loren mentioned I wouldn't bother replacing any coils unless they were badly corroded or cracked.

[Jake Raby]

One of our test cars has 38K on the clock.. During testing of the new 2.9 engine we found 2 of the 6 coils bad under heavy load.. Our other test car has 78K on it and it has had 3 coils replaced in the past 18 moths I have been using it for development work.

You can change all 6 in less than an hour with a 5mm hex...

[dcdrechsel]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

[Loren]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

[dcdrechsel]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

[Loren]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

[dcdrechsel]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

Cleaned MAF twice-couldn't find any air leaks-tried oil cap off test from shop manual and was ok .No other fault codes .

[Loren]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

Cleaned MAF twice-couldn't find any air leaks-tried oil cap off test from shop manual and was ok .No other fault codes .

What is your air mass flow reading at idle and no-load 2500RPM?

[dcdrechsel]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

Cleaned MAF twice-couldn't find any air leaks-tried oil cap off test from shop manual and was ok .No other fault codes .

What is your air mass flow reading at idle and no-load 2500RPM?

15.50 and 47.50

[Loren]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

Cleaned MAF twice-couldn't find any air leaks-tried oil cap off test from shop manual and was ok .No other fault codes .

What is your air mass flow reading at idle and no-load 2500RPM?

15.50 and 47.50

Well, it would appear your MAF is functioning within limits.

Unless you have a charcoal canister purge valve problem you have an air leak.

[dcdrechsel]

Jake -have you seen a flaky coil trip P1123 ? I am chasing an intermittent on a 99.

Dave

P1123 is likely a bad MAF or air purge valve or air leak problem. Please do a search P1123 has been covered here many many many times.

Loren -thank you for the reply .I have done a search and read /tried all the obvious things .What has me stumped is that it is really intermittent .For example the car will go 200 miles and set off P 1123 and at other times 75 miles or less .Right now I am north of 225 miles and the tra value is -.17 -I believe it trips at +/- .32 .My logic was a flaky coil could possibly set it off.Maybe it's a dumb question but it kinda seemed logical .

Dave

A bad coil pack would cause a fault on that one specific cylinder (i.e P0304 - misfire cylinder 4).

Have you tried a new MAF or cleaning the one you have?

Have you looked for air leaks? Any other fault codes?

Cleaned MAF twice-couldn't find any air leaks-tried oil cap off test from shop manual and was ok .No other fault codes .

What is your air mass flow reading at idle and no-load 2500RPM?

15.50 and 47.50

Well, it would appear your MAF is functioning within limits.

Unless you have a charcoal canister purge valve problem you have an air leak.

I will circle back on the purge valve and air leaks ..Thanks for the help