Mass airflow sensor
Thread Starter
7th Gear
Joined: Apr 2009
Posts: 7
Likes: 0
From: Grand Rapids Michigan
Mass airflow sensor
Well, I have looked and searched but cannot come up with this issue as previously discussed. I am new here so bear with me. I have an '87 C4 and I love the car, but not the 'finicky' issues that comes with it - specifically the smart computer. My issue is this:
After driving the car at highway speeds for about 15-20 minutes, the "Check Engine Soon" (or something to that affect) light comes on and stays on until I turn the car off. After doing so, the light re-sets and stays off (until I drive at highway speeds again as before).
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor". So, since we were not sure what was wrong with it, I had him install a new one. Again, the new one did the same thing so he saved me some bucks and re-installed the old one.
Can anyone shed some light on this issue? The car seems to perform fine when the light is lit, but if there ever is something wrong for real and the light comes on, I wouldn't know. This is driving me (and my mechanic) nuts! Help anyone?
After driving the car at highway speeds for about 15-20 minutes, the "Check Engine Soon" (or something to that affect) light comes on and stays on until I turn the car off. After doing so, the light re-sets and stays off (until I drive at highway speeds again as before).
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor". So, since we were not sure what was wrong with it, I had him install a new one. Again, the new one did the same thing so he saved me some bucks and re-installed the old one.
Can anyone shed some light on this issue? The car seems to perform fine when the light is lit, but if there ever is something wrong for real and the light comes on, I wouldn't know. This is driving me (and my mechanic) nuts! Help anyone?
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87
Well, I have looked and searched but cannot come up with this issue as previously discussed. I am new here so bear with me. I have an '87 C4 and I love the car, but not the 'finicky' issues that comes with it - specifically the smart computer. My issue is this:
After driving the car at highway speeds for about 15-20 minutes, the "Check Engine Soon" (or something to that affect) light comes on and stays on until I turn the car off. After doing so, the light re-sets and stays off (until I drive at highway speeds again as before).
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor". So, since we were not sure what was wrong with it, I had him install a new one. Again, the new one did the same thing so he saved me some bucks and re-installed the old one.
Can anyone shed some light on this issue? The car seems to perform fine when the light is lit, but if there ever is something wrong for real and the light comes on, I wouldn't know. This is driving me (and my mechanic) nuts! Help anyone?
After driving the car at highway speeds for about 15-20 minutes, the "Check Engine Soon" (or something to that affect) light comes on and stays on until I turn the car off. After doing so, the light re-sets and stays off (until I drive at highway speeds again as before).
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor". So, since we were not sure what was wrong with it, I had him install a new one. Again, the new one did the same thing so he saved me some bucks and re-installed the old one.
Can anyone shed some light on this issue? The car seems to perform fine when the light is lit, but if there ever is something wrong for real and the light comes on, I wouldn't know. This is driving me (and my mechanic) nuts! Help anyone?
Did you retrieve the codes? Sounds more like EGR to me.
Good luck.
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
Have you or your *mechanic* checked for ALL codes? What you are describing is also consistent with an fault in the EGR diagnostics. (I'm NOT saying that this is your problem - just that the parameters that you describe are consistent) Without referring to my shop manual but recalling from past experience, a faulty EGR system code will get set after so many minutes of driving at normal temperature at a prescribed speed (I recall it being in the vicinity of highway speed). Also, when an EGR system code is set, you vehicle will often run just fine and the light will reset itself too - I know because, I've been through it. If you need specifics on this and can't find it in a search, let me know and I'll get the details and specifics from my GM Shop Manual. But check for ALL set codes first.
Thread Starter
7th Gear
Joined: Apr 2009
Posts: 7
Likes: 0
From: Grand Rapids Michigan
I believe that the first time there were two codes (I do not recall the other one) but the second and third activations were both the same. Can the EGR system be 'cleaned' or this an expensive replace situation too?
(Thanks fore the quick response, guys)
(Thanks fore the quick response, guys)
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
There is a systematic diagnostic and elimination process outlined in the GM Shop Manual. Just because it says EGR, it does not necessarily mean EGR valve. For example it could be an EGR switch, solenoid, possible vacuum leak, etc. The Shop Manual takes you through a step-by-step process to narrow down the faulty part. I'm pretty sure if you do an advanced search on this site you will find a PDF of this elimination process that someone has shared earlier. Again, before going on a witchhunt - check you codes!
Cruising
Joined: Apr 2009
Posts: 13
Likes: 0
From: Welch West Virginia
stinger54
I have a 87 that is doing exactly the same thing and I was told to replace the burn off relays that are located behind the battery, I have not tried this yet but plan to. I spent 350.00 for a new maf and it did not do a thing, your luck was better then mine at the garage. Please if you fix your problem let me know this is about to drive me crazy.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
After driving the car at highway speeds for about 15-20 minutes, the "Check Engine Soon" (or something to that affect) light comes on and stays on until I turn the car off. After doing so, the light re-sets and stays off (until I drive at highway speeds again as before).
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor".
I have taken it to my service man and each time he checks the code it is the "mass airflow sensor".
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Thread Starter
7th Gear
Joined: Apr 2009
Posts: 7
Likes: 0
From: Grand Rapids Michigan
Stinger54 - If you check "rodj's" thread, he has been having the problem for years (not encouraging for me, but comforting that it's not serious I guess). But like I said before, I have the "GM Shop Manual" coming and maybe that will help me out. (It's nice to know I'm not alone - misery loves company...
.
Let me know if your remedy works and I'll keep you posted on my solution(?)
Thanks everyone.
. Let me know if your remedy works and I'll keep you posted on my solution(?)
Thanks everyone.
Cruising
Joined: Apr 2009
Posts: 13
Likes: 0
From: Welch West Virginia
Hey Swan, The manuals usually always make it harder then it has to be. I have found look at the simple things before you get all into it and find that it really was the burn off relay and the power relay, that replacement cost me 45.00 and fixed the problem as far as I can tell, how it continues to work.
Safety Car
Joined: Jan 2008
Posts: 3,939
Likes: 1
From: Vero Beach Florida
I have the 87 CD version of the FSM I do like the hard copy better, Bought it mainly if I go on a trip I can use it in my laptop. Just take you time and it makes more sence the more you use it, if its the same one I have learn to use the search in the index it will help