Bizzare

Tonya 740 · Post by **Tonya 740** » 30 Jan 2012, 00:17

Hi, I have a bizzare problem and no one seems to be able to figure it out. When I put my1991 740 wagon (nonturbo) in reverse it runs a little rough and when I put it back in drive the idle goes up and down. I shut off the car and restart it and it runs fine. I changed the plugs, wires, cap, rotor, ign. Coil, air filter I cleaned the throttle control valve, throttle body, Mass airflow, all electrical connectors, Fixed vacuum leaks. The car still had a surging idle from 800 to 2000 up down up down or stall but would run fine if I was moving or gave it a little rev to keep it going. Sometimes it would stall and wouldn?t start until it sat for awhile. So I changed the crankshaft position senor, nd woola car runs fantastic. I have no check eng light on the dash and I also changed the o2 sensor and tested the fuel injectors? So lets see how good you are, I love my car.
Thanks, Tonya

17yearsofboost · Post by **17yearsofboost** » 30 Jan 2012, 09:24

How many miles? ever service the Trans?

Post by **fazool** » 30 Jan 2012, 11:15

Tonya 740 wrote:...I have a bizzare problem and no one seems to be able to figure it out.

Well....I can't figure out what you are posting

Here is what information your post gave: You had a problem. You replaced a bunch of parts. You still had problems. You replaced another part and voila' the car runs fantastic with no CEL

OK......so what's your question?

Post by **billofdurham** » 30 Jan 2012, 11:47

Tonya 740, welcome to Matthew's Volvo Site.

So lets see how good you are,

Collectively we are usually very good but, like fazool, I too am wondering what the question is.

Bill.

Post by **bronxnativ** » 30 Jan 2012, 16:06

The title fits the description of the post. OP, please review the forums policies/rules; for example your title is extremely vague and lacks description of any issue.

Tonya 740 · Post by **Tonya 740** » 30 Jan 2012, 17:12

What Im trying to find out is "When I put my 1991 740 wagon (nonturbo) in reverse it runs a little rough and when I put it back in drive the idle goes up and down.I shut off the car and restart it and it runs fine." So why does the car shutter in reverse? I think it maybe the tranny mount. But why does it make the idle goes haywire until I shut off the car and start it again? I could under stand if the tranny had a control mod or relay or something but I dont believe it does. I dont know when the trans was last serviced but I dont know why it would mess with my RPM's.

Tonya 740 · Post by **Tonya 740** » 30 Jan 2012, 22:52

The more I think of it did any of you read my post? The issue is the first thing I talked about and followed up by telling you what I have done all ready. Why? so no one would ask questions like did you do this or that? I had others read it to be sure and they understood my post and wondered why you guys jumped on me for it.

Kirby J · Post by **Kirby J** » 30 Jan 2012, 23:55

2 thoughts on Bizarre:
Motor mounts or the transmission mount, if they are really bad, can cause the whole driveline to "bind" a bit. This puts an increased load on the engine, which may account for your drop in idle, the surge is the system trying to compensate. When you restart and pull forward a bit, you "unbind" the drive train.

Or, what I did once, the plug on my throttle body and idle adjustment valve are identical. After doing a throttle body cleaning I hooked them up wrong. LOTS of weird idle problems after that. I played with it for months before I figured that one out.

Kirby J
93 940 Rex Regina 430K

Post by **MoVolvos** » 30 Jan 2012, 23:59

"So I changed the crankshaft position senor, nd woola car runs fantastic. I have no check eng light on the dash and I also changed the o2 sensor and tested the fuel injectors? So lets see how good you are, I love my car."
-
From your post it looks like your car is running great at this time is that correct? Meaning the problem in solved right?

Tonya 740 · Post by **Tonya 740** » 31 Jan 2012, 00:32

Kirby J Im impressed thats the best answer I have ever heard so far Ill let you know how it works out.