1988 325ic feeling sluggish

[leonthelion93]

Hey there everyone!

I recently purchased a 1988 e30 vert as my very first project car. My knowledge on fixing and diagnosing cars is extremely limited as I never got the opportunity to fix cars when I was younger.

So the issue I am currently having is that the car feels sluggish. EXTREMELY sluggish. It drove great when I first purchased it, but about 2 weeks after I purchased it I got an oil change(the original owner had used 5w30, I searched and found many people said to use 20w50) I parked the car and woke up next morning to something that felt quite sluggish. Like the car almost struggles to accelerate even when I floor the throttle.

As I stated I am extremely new to fixing cars, but I figured the only way to learn is to read and ask questions, so please be easy! What are some things I could check and/or look? Any advice is priceless, small or large. I am learning new things about the car day by day.

Cheers!

[dnguyen1963]

Very first thing to do is to have a shop perform a smoke test for you then fix any vacuum leaks that you might have. Do a valve adjustment next. Check an replace O2 sensor if it has not been replaced and you car has over 100K. Check all ignition wires and spark plugs - replace if necessary. Check fuel pressure and filter for clogging. Most importantly, get your self a copy of the Bentley Manual. Timing belt and water pump should not be ignored. There are many other things, but do these first. Use Google to find videos for these repairs.

[smokeyyank]

Welcome! I also just recently picked up my first e30, but I have been wrenching on cars for a while. What I can tell you from my experience is while the car isn't hard to work on, it takes a little "getting" used to, but it can be tons of fun. To elaborate on what dnguyen1963 said I would start with checking the easy visual things before tearing into it.

-Check you spark plugs: Simply pull them out, all of them, and go to google and pull up "spark plug fouling" and compare your plugs to those images. That right there will give you a good indicator of how your engine is doing and what issues you may be having.

-Check your plug wires: Look for any cracks, excessive oil or wear. Also I would grab some spark plug grease and just put a little on before putting the boots back on.

-Check your cap and rotor: Little bit more difficult to get to but again can probably be something that may cause issues. Check to make sure there aren't any cracks or that the points aren't completely wore out.

-Check your fuel pressure: You can get a loaner fuel pressure tester at the auto part store. Plenty of info on how to check it.

-I would replace the fuel filter unless it's documented that it was done recently. it's easy and cheap to do and needs to be done anyways.

-Check your intake boot and the rest of the air intake system. Make sure your intake boot doesn't have any cracks, they are notorious for cracking and poor engine performance is a result. I would also check the air filter and replace with a factory one if not already done. My car had a crappy fram that was dirty as heck. After I replaced it and cleaned out the intake it drastically helped with some issues but not all.

-Get some MAF or carb cleaner and clean off your throttle body and the intake. Mine was completely covered in oil. In part because the crank case breather hose recirculates oil back in the intake and I don't think the PO every cleaned it. It literally was all the way in the intake at the ports.

-Check to make sure all the hoses are connected. Not sure who did the oil change but maybe something got knocked loose, especially if they changed the air filter. Personally I don't think a change in oil weight would cause the car to ran drastically different but I could happen or maybe just unlocked some other causes.

-Replace your timing belt: Unless you have it documented from the PO that it was recently done you are asking for major problems. I am in the process of doing it right now, along with a bunch of other things, and while it's not hard to do its very time consuming especially if you've never done it before I would say 2 days and that is really a stretch, most people say a little over a half a day, but it depends on what you are also doing. There are plenty of videos and write ups on how to do it, but they miss a lot of info or "assume" you know how to do something. For example take of the accessory belts. Well if you've never done it it's not just a simple bolt you take off. If you aren't comfortable doing it yourself be prepared to spend a pretty penny to take it somewhere. Honestly if you have the tools, time and patience almost anyone can do it. Also it's not just a get in there and swap one part either so be prepared to do more than just the belt. With out even looking at the car, I would suggest water pump, cam shaft seals, belts and radiator hoses. I literally have replaced majority of the top end because I start working and notice something that needs to be replaced and since I'm already in there I would rather do it now than take it all a part to do it in a few months.

Also a few other things to check out that I have found can cause problems
-The TPS (throttle position sensor)
-Faulty AFM (air flow meter)
-Bad CPS (crank position sensor)
-Vacuum leaks (smoke test will solve that)

Cheers

[leonthelion93]

Very first thing to do is to have a shop perform a smoke test for you then fix any vacuum leaks that you might have. Do a valve adjustment next. Check an replace O2 sensor if it has not been replaced and you car has over 100K. Check all ignition wires and spark plugs - replace if necessary. Check fuel pressure and filter for clogging. Most importantly, get your self a copy of the Bentley Manual. Timing belt and water pump should not be ignored. There are many other things, but do these first. Use Google to find videos for these repairs.

Okay I will definitely have to find a near by shop that could do a smoke test for me. Thanks for the insight! What exactly is a valve adjustment?
I definitely want to be able to do as much as I can myself without having to take it to a shop, because well, it's usually expensive and I won't learn a thing letting someone else fix my project for me, hehe. And certainly going to get a Bentley Manual ASAP. On the top of my priority list right now.

Thanks for the response!

[leonthelion93]

Welcome! I also just recently picked up my first e30, but I have been wrenching on cars for a while. What I can tell you from my experience is while the car isn't hard to work on, it takes a little "getting" used to, but it can be tons of fun. To elaborate on what dnguyen1963 said I would start with checking the easy visual things before tearing into it.

-Check you spark plugs: Simply pull them out, all of them, and go to google and pull up "spark plug fouling" and compare your plugs to those images. That right there will give you a good indicator of how your engine is doing and what issues you may be having.

-Check your plug wires: Look for any cracks, excessive oil or wear. Also I would grab some spark plug grease and just put a little on before putting the boots back on.

-Check your cap and rotor: Little bit more difficult to get to but again can probably be something that may cause issues. Check to make sure there aren't any cracks or that the points aren't completely wore out.

-Check your fuel pressure: You can get a loaner fuel pressure tester at the auto part store. Plenty of info on how to check it.

-I would replace the fuel filter unless it's documented that it was done recently. it's easy and cheap to do and needs to be done anyways.

-Check your intake boot and the rest of the air intake system. Make sure your intake boot doesn't have any cracks, they are notorious for cracking and poor engine performance is a result. I would also check the air filter and replace with a factory one if not already done. My car had a crappy fram that was dirty as heck. After I replaced it and cleaned out the intake it drastically helped with some issues but not all.

-Get some MAF or carb cleaner and clean off your throttle body and the intake. Mine was completely covered in oil. In part because the crank case breather hose recirculates oil back in the intake and I don't think the PO every cleaned it. It literally was all the way in the intake at the ports.

-Check to make sure all the hoses are connected. Not sure who did the oil change but maybe something got knocked loose, especially if they changed the air filter. Personally I don't think a change in oil weight would cause the car to ran drastically different but I could happen or maybe just unlocked some other causes.

-Replace your timing belt: Unless you have it documented from the PO that it was recently done you are asking for major problems. I am in the process of doing it right now, along with a bunch of other things, and while it's not hard to do its very time consuming especially if you've never done it before I would say 2 days and that is really a stretch, most people say a little over a half a day, but it depends on what you are also doing. There are plenty of videos and write ups on how to do it, but they miss a lot of info or "assume" you know how to do something. For example take of the accessory belts. Well if you've never done it it's not just a simple bolt you take off. If you aren't comfortable doing it yourself be prepared to spend a pretty penny to take it somewhere. Honestly if you have the tools, time and patience almost anyone can do it. Also it's not just a get in there and swap one part either so be prepared to do more than just the belt. With out even looking at the car, I would suggest water pump, cam shaft seals, belts and radiator hoses. I literally have replaced majority of the top end because I start working and notice something that needs to be replaced and since I'm already in there I would rather do it now than take it all a part to do it in a few months.

Also a few other things to check out that I have found can cause problems
-The TPS (throttle position sensor)
-Faulty AFM (air flow meter)
-Bad CPS (crank position sensor)
-Vacuum leaks (smoke test will solve that)

Cheers

Your indepth response is very much appreciated.

As for the plugs and wires, I recently replaced them with what seems like it doesn't fit as snug as the previous spark plugs, but I will definitely check into them again and get some plug grease.

What exactly is cap and rotor referring to? I have access to a lift so maybe that could help in accessing areas that may be usually more difficult if that helps!

As for MAF, I definitely have seen a lot of post about MAFs but I still have no idea what that is lol. I'm a little reluctant to remove my intake as I've never even bolted anything on to my car besides a license plate frame, but I did change my air filter so it's only a few more bolts until I get to the throttle body so I will just have to get to it.

Now as for the timing belt, yes I've definitely considered having to change that, but idea of possibly ruining my vehicles scares me lol. Hopefully I can find some buddies out here that know a thing or two about changing one and we can set a date to get to that.

My next diagnosis consist of checking the fuel pressure as recommended by another e30 owner. I'm sure it won't be too hard, but I'm hoping that replacing the fuel filter won't be costly and difficult. I'll update you on what I am able to get done in next few days.

Can't thank you enough,
Cheers!!

[smokeyyank]

No worries, glad to help.

-As for the plugs are wires, what did your replace them with? Again I would make sure to stick with OEM parts. Also did you check the gap on the plugs before putting them in? Most plugs are pre gapped but always good to check. Should be .27 or.28 for factory gap. Also make sure to use anti seize on the threads. Removing a seized plug will drive you crazy.

-The cap and rotor is the distributor. It sends the signal to the spark plug to "fire" based on timing. It's not hard to check really. Just 3 10mm bolt and pull it off the examine it.

-Technically it not a MAF (mass air flow meter), the AFM has a "door" on it that will send a signal to the ECM for how much air is coming through. Part of the reason vacuum cause so many problems it the AFM won't read that air and the engine gets goofy signals. Pretty simple to take off and you won't jack it up unless you really try to. Just pull it off and make sure the door isn't getting stuck or have something stuck in it.

- Timing belt isn't terribly that hard. It seems hard but really it's not. Just takes a lot of time because you have to remove so many parts. Check out youtube and look for E30source he has videos that do a good job of explaining what to do. Also he has a video about valve adjustments. Again not hard just takes some time. There is also a DIY thread on here about doing a timing belt that has good info. It is step by step the only things I learned that no one really mentioned was how to remove the fan (super easy once I figured it out) and how to release tension on the accessory belts. The car's have a goofy nut that you need to loosen in order to release tension. Just something I had never seen before.

-Fuel filter is easy and cheap, literally a $10 part and 30 minutes. Make sure for any part you replace you stick with OEM, don't go to autozone or box stores. I went to Blunttech for all my parts. He's super easy to work with and willing to match prices if you find them cheaper.

[leonthelion93]

No worries, glad to help.

-As for the plugs are wires, what did your replace them with? Again I would make sure to stick with OEM parts. Also did you check the gap on the plugs before putting them in? Most plugs are pre gapped but always good to check. Should be .27 or.28 for factory gap. Also make sure to use anti seize on the threads. Removing a seized plug will drive you crazy.

-The cap and rotor is the distributor. It sends the signal to the spark plug to "fire" based on timing. It's not hard to check really. Just 3 10mm bolt and pull it off the examine it.

-Technically it not a MAF (mass air flow meter), the AFM has a "door" on it that will send a signal to the ECM for how much air is coming through. Part of the reason vacuum cause so many problems it the AFM won't read that air and the engine gets goofy signals. Pretty simple to take off and you won't jack it up unless you really try to. Just pull it off and make sure the door isn't getting stuck or have something stuck in it.

- Timing belt isn't terribly that hard. It seems hard but really it's not. Just takes a lot of time because you have to remove so many parts. Check out youtube and look for E30source he has videos that do a good job of explaining what to do. Also he has a video about valve adjustments. Again not hard just takes some time. There is also a DIY thread on here about doing a timing belt that has good info. It is step by step the only things I learned that no one really mentioned was how to remove the fan (super easy once I figured it out) and how to release tension on the accessory belts. The car's have a goofy nut that you need to loosen in order to release tension. Just something I had never seen before.

-Fuel filter is easy and cheap, literally a $10 part and 30 minutes. Make sure for any part you replace you stick with OEM, don't go to autozone or box stores. I went to Blunttech for all my parts. He's super easy to work with and willing to match prices if you find them cheaper.

I replaced the plugs with OEM parts so they should be good to go. Hmmm I should probably get some anti seize haha D:

Okay that's too easy. First thing tomorrow I will check out the distributor.

Hmmm I'll have to check up on the AFM then. I'll dig around also tomorrow to see what I can find!

Oh okay then that's no biggy. So there's 3 good things I can do for my car once I find a replacement for the fuel filter.

Hopefully something as simple as one of these fixes will open a door or two to the issue. I'll let you know what I find!

[dnguyen1963]

Okay I will definitely have to find a near by shop that could do a smoke test for me. Thanks for the insight! What exactly is a valve adjustment?
I definitely want to be able to do as much as I can myself without having to take it to a shop, because well, it's usually expensive and I won't learn a thing letting someone else fix my project for me, hehe. And certainly going to get a Bentley Manual ASAP. On the top of my priority list right now.

Thanks for the response!

https://www.youtube.com/watch?v=tkkKGcDXnz8

[leonthelion93]

https://www.youtube.com/watch?v=tkkKGcDXnz8

Oh wow this is an awesome indepth video. Thanks!

[leonthelion93]

Update:

So I found this thread that told me to check my spark plugs by removing 1 at a time and if the RPM drops then you know it's firing. Well oddly enough (from left to right) the 2nd and 3rd one's don't react and the RPM does not drop when each of those are pulled. I just replaced those though, so what do you think could have caused that?

[dnguyen1963]

Update:

So I found this thread that told me to check my spark plugs by removing 1 at a time and if the RPM drops then you know it's firing. Well oddly enough (from left to right) the 2nd and 3rd one's don't react and the RPM does not drop when each of those are pulled. I just replaced those though, so what do you think could have caused that?

Do this...

https://www.youtube.com/watch?v=q2DNJ8t7mzU

[leonthelion93]

Do this...

https://www.youtube.com/watch?v=q2DNJ8t7mzU

Thanks! Will be doing this tomorrow.

Btw, you don't happen to be Vietnamese also, are you?

[dnguyen1963]

Thanks! Will be doing this tomorrow.

Btw, you don't happen to be Vietnamese also, are you?

Yes, I am.

[leonthelion93]

Yes, I am.

Oh okay just wondering! Well I did the test, and I also replaced my fuel filter, which leak out dark brown fuel so I'm assuming it was a good idea. I got about 5.6V from the two spark plugs wires and got about 6V from the others. So I'm assuming there's a bit of a voltage drop somewhere in there. Is it something too significant where I'd have to change my wires or anything?

[jlevie]

There is good advice scattered through this thread, but I'll stick an oar in and offer my suggestions:

1) Have a smoke test run to check for intake leaks and repair as indicated,
2) Have the rail fuel pressure checked and repair as indicated.
3) Adjust the valves.
4) If the car has 100k on it, replace the entire cooling system, including the fan clutch, and the O2 sensors.
5) Unless you have proof that the timing belt was recently changed, replace it.
6) Replace the ignition wires, distributor cap & rotor with new OE/OEM parts. Use NGK ZGR5A plugs.
7) Change all fluids & oil filter (Mobil1, BMW, or Mann are best choices for the filter).
8) Have an experienced BMW tech inspect the suspension for worn or damaged parts. It would be a safe bet to say that the car needs new shocks, struts, and upper shock/strut mounts.

There are other things that might need attention like the CPS and TPS and possibly the AFM. But do the other stuff first.