Problem diagnosis please!!! Engine cutting out

[04F2504X4]

My car has been running fine until now.

It happens more often when I shift then go to accelerate but also occurs under just acceleration. The car will just fall on top of itself lose power and after about 3 seconds kick back in and keep going.

It happens more under hard acceleration. I havent been able to get it to do it in 1st gear if that helps at all?



I searched but most problems are a little different then mine. So if anyone could narrow it down thatd be awesome! I dont have the money to go and replace 5 different things.

[bcrdukes]

1. Do the stomp test (if applicable.) See what codes you get.
2. What have you checked so far?
3. Describe the problem in more detail.

Do steps 1 to 3 and report back. Thanks

[04F2504X4]

1. Do the stomp test (if applicable.) See what codes you get.
2. What have you checked so far?
3. Describe the problem in more detail.

Do steps 1 to 3 and report back. Thanks

I have a 1986 325e. Doesnt have engine codes right???

2. I have checked vacuum hoses for leaks.


3. So.. ill be going from 1st shift at 3k (let go of gas) and when i go to give it gas in second. The car just falls on top of itself...has no power and ill hold the throttle down then all the sudden all power comes back and im off.
This problem will do it at any moment during acceleration but it MOSTLY does it after i left go of the gas to shift.

The car itself stays running but lunges me forwards due to the sudden loss in acceleration. Then the power is suddenly back and im off again.


Thanks for your quick reply so far! Hope some of that helps.

[CoClimber]

I spent a long time working on a similar problem in that the engine would just die for a second or two. The tach would go to zero and the MPG gauge would cycle through. In my case, it was the coil. It was cracked and I think it was putting a high voltage spike on the 12 volt line, causing the computer to reset. I don't think that is your problem but I'm wondering if you have a ground strap issue. When you accelerate, the engine will twist, which might cause the ground wire to move and fail. This could cause the computer to act up.

[04F2504X4]

I spent a long time working on a similar problem in that the engine would just die for a second or two. The tach would go to zero and the MPG gauge would cycle through. In my case, it was the coil. It was cracked and I think it was putting a high voltage spike on the 12 volt line, causing the computer to reset. I don't think that is your problem but I'm wondering if you have a ground strap issue. When you accelerate, the engine will twist, which might cause the ground wire to move and fail. This could cause the computer to act up.

Well my tach or gauges dont do anything crazy when it happens. Thanks for the input though

[E30_fiend]

1. Air Flow Meter. Change out with known good one. See if problem persists.

2. Spark Plugs. Check for fouled plugs.

3. Distributor Cap and Rotor. Pull the cap off and check the contacts for build up. Also check rotor contact.


Check those three things. One is bound to be bad. Especially on an 86 e30. I highly doubt the AFM has been replaced in the 23 years since its been around. The plugs, wires, cap and rotor have more than likely been changed before.




Taylor

[04F2504X4]

1. Air Flow Meter. Change out with known good one. See if problem persists.

2. Spark Plugs. Check for fouled plugs.

3. Distributor Cap and Rotor. Pull the cap off and check the contacts for build up. Also check rotor contact.


Check those three things. One is bound to be bad. Especially on an 86 e30. I highly doubt the AFM has been replaced in the 23 years since its been around. The plugs, wires, cap and rotor have more than likely been changed before.




Taylor

Cool thanks! Ill check em all tomorrow. I kkow the plugs are good i did those the day i bought it.

[BlUe E30]

also mine did the EXACT same thing it took me 3 months to figure it out... it was the main relay believe it or not, stock relay over 20 years old the contacts were not holding a new main relay and it fixed the problem totally! also check to see if your ckp sensor wire is rubbing on the back of one of your pulleys and grounding out taking the rpm signal away

[StereoInstaller1]

Don't waste your time on ANY of the listed issues before testing the main relay.

You can make a jumper to test with, but you have to make 3 connections at the same time. If you have a set of crimpers, use 3) 1/4" spade terminals with a few inches of wire between them.

Look on the side of the relay, there is a diagram. You would want to connect "30" with BOTH of the "87"s, and the car will start.

These relays are only good for 20 years or so, but the replacement will crap out in 5 or so (thank you China).

65% of the time, the "car dies and restarts fine" type problems are bad main relays.

If both "87s" go dead, the tach freaks out. If only 1 goes out, you lose the ECU and the car dies...sometimes never to restart again.

Make that jumper, bypass that relay.

GL!
Luke

[BlUe E30]

^^^ what he said and that was my fix!

[04F2504X4]

If both "87s" go dead, the tach freaks out. If only 1 goes out, you lose the ECU and the car dies...sometimes never to restart again.

Make that jumper, bypass that relay.

GL!
Luke[/quote]


Thank you very much luke. I read through another post by you while i was searching and just saw the main relay is not universal with all the rest. When i was at the scrap yard i took the relays out of a better car and put them in at random thinking they all looked the exact same. Im going to go ahead and guess i put a wrong one in the spot. That was over 2 months ago? But hmm i dunno maybe it just managed to work untill now.

Edit***** I went to http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf --- I cannot seem to find where the "main relay" actually is? I only see un-loader, wipers, headlights, high speed, fogs, and horn. None called main? Or when i search main relay says none are found. Mind letting me know??

[bcrdukes]

If you stand on the driver side of the car at the engine bay, look at your AFM. There is a "black box" between the AFM and the side of the engine bay that you can open up (there is a clip you can push.) Lift the box open. You will see 3 relays. From the front of the engine to the firewall goes like this:

Main Relay - Fuel Pump Relay - O2 Relay

The Main Relay is not elevated while the Fuel Pump and O2 relay are. The main relay will have 5 prongs and will only go in one way, the side of the main relay will have these tabs popping out which will align with the holding clips.

[StereoInstaller1]

If you stand on the driver side of the car at the engine bay, look at your AFM. There is a "black box" between the AFM and the side of the engine bay that you can open up (there is a clip you can push.) Lift the box open. You will see 3 relays. From the front of the engine to the firewall goes like this:

Main Relay - Fuel Pump Relay - O2 Relay

The Main Relay is not elevated while the Fuel Pump and O2 relay are. The main relay will have 5 prongs and will only go in one way, the side of the main relay will have these tabs popping out which will align with the holding clips.

Yup, on the left shock tower.

[bcrdukes]

^
Thanks! I knew I was missing that mental image. :p

[hayes3054]

My car was having the exact same problem tonight. It would cruise along fine till I got to a hill or needed to accelerate. then it would cut out. I thought it was fuel related. main relay - eh? where is a good source for one?
Thanks,
Mike