Idle/starting problem - solved!
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Pro
Joined: Jun 2001
Posts: 509
Likes: 5
From: Edmonds WA
Idle/starting problem - solved!
A few months ago my 87 began having an intermittent starting problem... about 2 of every 10 starts it would just die after it fired up and as soon as I let off the starter. I was able to start it only by giving it part throttle, but then it would die at stop signs. Starting it later, up after work for example, it would start and run fine. I unplugged the MAF and it started fine, but replacing the MAF and the relays didn't solve the problem. :( I had no Check Engine light. It was difficult to diagnose because it happened so unpredictably.
I used some intake cleaner on the throttle body and checked all the vacuum lines... the problem kept happening. I collected some data using a laptop because I figured after spending a few hundred dollars on the MAF and not solving the problem, I needed to do better diagnosis. I was able to record data a few times when the problem was happening, but I couldn't tell exactly what was causing the problem... even after quite a bit of analysis. :banghead:
I finally took the throttle body completely off and apart and cleaned it thoroughly, replaced the IAC (Idle Air Control) valve, put it all back together, set the idle speed and the throttle position sensor and it seems to have solved the problem. :hurray: I suspect the IAC was the culprit, as it was pretty cruddy looking... I decided to replace it rather than clean it since I didn't want to dig into the whole intake again if it turned out cleaning the old one didn't solve the problem.
It's been starting and running fine for over a month now (I decided to wait a good long while to make sure I'd really solved the problem). I hope sharing this story helps someone else along the way, since the intermittent problems can be such a bear to track down.
Many thanks to all the help I got from members of the forum, especially okinawa86vette, 65Z01, "ol,RJ", 88_Vette and HighHopes85 :flag
:cheers:
I used some intake cleaner on the throttle body and checked all the vacuum lines... the problem kept happening. I collected some data using a laptop because I figured after spending a few hundred dollars on the MAF and not solving the problem, I needed to do better diagnosis. I was able to record data a few times when the problem was happening, but I couldn't tell exactly what was causing the problem... even after quite a bit of analysis. :banghead:
I finally took the throttle body completely off and apart and cleaned it thoroughly, replaced the IAC (Idle Air Control) valve, put it all back together, set the idle speed and the throttle position sensor and it seems to have solved the problem. :hurray: I suspect the IAC was the culprit, as it was pretty cruddy looking... I decided to replace it rather than clean it since I didn't want to dig into the whole intake again if it turned out cleaning the old one didn't solve the problem.
It's been starting and running fine for over a month now (I decided to wait a good long while to make sure I'd really solved the problem). I hope sharing this story helps someone else along the way, since the intermittent problems can be such a bear to track down.
Many thanks to all the help I got from members of the forum, especially okinawa86vette, 65Z01, "ol,RJ", 88_Vette and HighHopes85 :flag
:cheers:
