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New - tech quiz by Francis T
Started on: 11-19-2014 12:40 AM
Replies: 13 (295 views)
Last post by: Francis T on 11-21-2014 11:40 AM
Francis T
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Report this Post11-19-2014 12:40 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
Add your helpful info (another multiple choice tech quiz question) I'll start it off two.

1st question: Which can cause engine damage -even catastrophic-
1 - Running High oct 93+ in low compression engine
2 - Running Low oct 87 in high compression or boosted engine
answers:
A - 1
B - 2
C - both 1 & 2 can
D - none of the above

2nd question Fiero ignition coils tend to malfunction more than other cars because:
answers:
A - poor quality
B - they get too hot
C - they don't, it's a connector problem
D - both A & B

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dobey
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Report this Post11-19-2014 09:10 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Francis T:

Add your helpful info (another multiple choice tech quiz question) I'll start it off two.

1st question: Which can cause engine damage -even catastrophic-
1 - Running High oct 93+ in low compression engine
2 - Running Low oct 87 in high compression or boosted engine
answers:
A - 1
B - 2
C - both 1 & 2 can
D - none of the above

2nd question Fiero ignition coils tend to malfunction more than other cars because:
answers:
A - poor quality
B - they get too hot
C - they don't, it's a connector problem
D - both A & B


1st question: E - It depends on a lot of variables which are not quantified in this question.
2nd question: E - What is more than other cars exactly? I've never had a coil fail in a Fiero (or any other car I've owned). What fails most often in the Fiero ignition system is the Ignition Control Module.
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edfiero
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Report this Post11-19-2014 11:35 AM Click Here to See the Profile for edfieroClick Here to Email edfieroSend a Private Message to edfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't know of any damage to the CAR from running High Octane in a low compression car.
The only damage is to your Wallet !!

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dobey
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Report this Post11-19-2014 01:41 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by edfiero:

I don't know of any damage to the CAR from running High Octane in a low compression car.
The only damage is to your Wallet !!


Depends on the engine, but running high octane fuel in an engine designed for lower octane, without appropriate changes to require the higher anti-knock index of the fuel, can result in incomplete burn of the fuel, which is equivalent to running rich, which can over time damage the catalytic converter, result in carbon build up on the O2 sensor and spark plugs, and cause the ECM to constantly switch between rich/lean scenarios. Depending on the fuel supplier you get the higher octane from, the fuel may have more cleaning agents which might help prevent excessive carbon build-up, but with 10% ethanol mixtures, running higher AKI fuel for the additional cleaners, is not needed, as the ethanol itself is a quite good cleaning agent.
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tebailey
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Report this Post11-19-2014 05:29 PM Click Here to See the Profile for tebaileyClick Here to Email tebaileySend a Private Message to tebaileyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have seen damage from running low octane in high compression engines, it's not kind to the tops of pistons. If you drive with a light foot though you can get away with it for a while.
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Report this Post11-20-2014 09:06 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by tebailey:

I have seen damage from running low octane in high compression engines, it's not kind to the tops of pistons. If you drive with a light foot though you can get away with it for a while.


It depends. What is high compression exactly? 10:1? 12:1? 16:1? Modern direct injection engines don't necessarily need higher octane fuels for the higher compression ratios or boost. Many are also turbocharged with 10:1 or higher compression ratio, and still running on regular 87 octane fuel. With accurate measurement and control of cam and spark timing, fuel mixture, knock, and other variables, modern ECMs can do quite a bit for varying fuel quality conditions.

There are way too many variables to make broad generalized assertions, as are assumed in the "quiz" questions above.
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sardonyx247
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Report this Post11-20-2014 09:25 AM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
#1 is B as boost (and higher compression) requires more octane to suppress knock, (every point of octane is worth a lb of boost)

#2 is also B as Fiero engine bays tend to run a bit hotter than other cars, poor quailty would also translate to other car also

Did I win?
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Stubby79
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Report this Post11-20-2014 11:19 AM Click Here to See the Profile for Stubby79Send a Private Message to Stubby79Edit/Delete MessageReply w/QuoteDirect Link to This Post
What's an engine?
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Francis T
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Report this Post11-21-2014 12:53 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Stubby79:

What's an engine?

THE WINNER
Not really but still a great reply.
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Francis T
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Report this Post11-21-2014 01:35 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post

Francis T

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Member since Oct 2003
With respect my first question, I did not go into specific details to avoid confusing aspiring young gear-heads.
By damage, something becomes useless like a piston with a hole in etc. As pointed out by -sorry I forgot whom, but I'll edit this later-, yes, high oct in a low compression -let's say any Norm Aspri engine with lower than 9:1- engine can -if driven long enough have fouled plugs, a dirty o2 malfunctioning sensor and so fourth. Thank said, the answer is both 1 & 2, with 2 low in a high the most damaging.

With respect to ign coil question, A lot of Fiero folks -more than owners of other car makes- go through lots coils. Do a search here and see.
I will state the correct answer/or/answers in my next post.

How about adding your questions people?
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Report this Post11-21-2014 06:12 AM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Francis T:

yes, high oct in a low compression -let's say any Norm Aspri engine with lower than 9:1- engine can -if driven long enough have fouled plugs, a dirty o2 malfunctioning sensor and so fourth. Thank said, the answer is both 1 & 2,

How about adding your questions people?


Only if it missfires alot, and most of the time the high octane has more cleaners/additives in it, thus helps carbon build up. If it doesn't missfire then the above won't happen.

And foulded plugs, or even dirty o2 malfunctioning sensor will not cause a hole in a piston or damage. as that kind of damage would happen during wide open throttle not cruising, and at WOT the ECM always goes the richer of what the ECM learned or the stock code, to avoid damage, IE it won't lean out at WOT. and if the dirty o2 malfunctioning sensor was malfunctioning long enough to cause a problem it would trip a code, then it would be the drivers fault for lack of maintance. Thus not the octane ratings fault, so I stand by my above answers.

 
quote
Originally posted by Francis T:

How about adding your questions people?


Most of the posts are questions.


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larry mimbs
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Report this Post11-21-2014 08:48 AM Click Here to See the Profile for larry mimbsClick Here to Email larry mimbsSend a Private Message to larry mimbsEdit/Delete MessageReply w/QuoteDirect Link to This Post
High octane in a lo comp engine with normal ignition timing will seriously stress the cooling system.
The high octane burns slower, which means it is still burning as the exhaust valve opens. Thus you get higher cylinder head and exhaust temps.
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dobey
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Report this Post11-21-2014 11:23 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Francis T:

With respect my first question, I did not go into specific details to avoid confusing aspiring young gear-heads.
By damage, something becomes useless like a piston with a hole in etc. As pointed out by -sorry I forgot whom, but I'll edit this later-, yes, high oct in a low compression -let's say any Norm Aspri engine with lower than 9:1- engine can -if driven long enough have fouled plugs, a dirty o2 malfunctioning sensor and so fourth. Thank said, the answer is both 1 & 2, with 2 low in a high the most damaging.

With respect to ign coil question, A lot of Fiero folks -more than owners of other car makes- go through lots coils. Do a search here and see.
I will state the correct answer/or/answers in my next post.


With respect to your experiences, it's not about confusing aspiring young gear-heads. What causes confusion, is incomplete information, touted as correct information, when it does not necessarily apply. There are huge differences in what will happen in any of these conditions, for a 50 year old carbed SBC, a 30 year old Fiero 2.8 or 2.5, a 3800 swap, or the current direct injection engines.

And with the coils, again, any bone stock Fiero is 25-30 years old at this point. Parts do not have infinite life spans. Ignition coils are built with a design specification to withstand a certain number of firing cycles. When that number of cycles is approached, you can expect the coil to stop working soon enough. Loose connection for the coil to distributor wire (or any of the plug wires) can also result in arcing, which will create carbon deposits on the electrodes, which can cause premature failure. Any number of things could have caused a 30 year old coil to fail. Heat, cold, and connection problems are a few of the possible reasons. They do not necessarily fail any more than any other car makes though.

The problem with your questions is that they are too vague and subjective. They are not direct technical questions. Accurate technical knowledge doesn't give correct answers to them. The correct answer can only be guessed, by trying to guess what your own opinion is. I will try to think of a few better questions which are objective and purely technical instead, but I haven't had time to think of any yet.
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Francis T
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Report this Post11-21-2014 11:40 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
As for question 2 coil failures the answer is:
Ignition related corroded connectors. In the process of changing out a coil connector contacts get wiped which often cleans them enough allowing the new coil work. BTW if you put the old coil back you may find it's suddenly good. Thus, if you lose ignition re-seat the connectors on the coil and those at the base of the distributor a few times before you dash off to by new parts. Oh, and if the fix works, replace the connectors. This diag method can also be applied to other suspected failing units such as o2, MAP, MAS, TPS senors, and other items.

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