Expert: Ara Date: 2/24/2008 Subject: 1986 Honda Accord Engine Surge
Question QUESTION: When driving is Drive (4th gear Automatic) The RPM fluctuates causing the transmission to down shift to 3rd. This then shifts back to 4th. The Shift selector is in the D4 position. This repeats when in that gear. I have to select D3 for it to stop. The transmission fluid is clean and at the right level. No sign of it being burnt. This is very frustrating as I can't do Hwy speeds in D3.
ANSWER: What is the engine speed where this happens?
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QUESTION: The RPM is @ 1500 to 2000 when in D4, Road speed about 50 km/h but when the surging starts the RPM fluctuates up to 3000. When I put the selector in D3 the RPM ranges between 3000 @ 60 km/h, to 4000 @ 80 km/h.
ANSWER: Check the EGR(Exhaust Gas Recirculation) valve & passages.
If the EGR is faulty or the ports are clogged, it will have the symptoms you have described.
By the way, is the vehicle the DX,LX or EX model?
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QUESTION: The dealer told me that it was just an Accord type S.. They would not even look at my car. I guess they don't have time for cars this old.
CarFax: when I put in the V.I.N. # said it was a 1986 HONDA ACCORD DX HATCHBACK 2 DR 2.0L L4 2BL / FRONT WHEEL DRIVE.
I went to a garage today and described my problem and they said that it was the Coolant Pressure Sensor. The also told me that the Vacuum Advance unit, was cracked. The hoses were not even attached. The Coolant Pressure Sensor has 2 vacuum hose fittings, one is busted and covered with tape. The hose is also plugged off. I was told if I replace the Vacuum Advance unit, the Coolant Pressure Sensor and reattach the hoses, should correct the problem.
Now with what you tell me I am totally confused. I don't know what to fix first. Remember that this surge only occurs when driving in D4, not in any other gear. It idles @ about 700RPM.
Answer You need to first take care of all the broken parts.
All vacuum hoses NEED to be attached to something, they are not meant to be plugged off or just hanging somewhere.
There is no such thing as "Coolant Pressure Sensor".
I don't what they are talking about.
But, if they guarantee their work and told you that it WILL take care of the problem, then you should have them fix it.
