84 325e strange power issue

[e30patalohas]

Hi all I have a pretty well sorted out e30 that I've been into for about a year and a half. I've done a lot of regular maintenance (plugs, cap/rotor/cooling system, timing belt, valve adj., coolant temp. sensor, remanufactured injectors, FPR, Fuel pumps/filter/lines, intake hoses, brake master cyl., etc., etc.)

It runs very nicely, but the last two things that bug me are from cold start it will bog 2-3 times if you try to accelerate up my driveway. Pressing the gas pedal gives power then power dies out until you press the gas a lot more then it catches up and accelerates quickly.

The second issue is that once the engine is warmed up and in open loop, it runs great but very occasionally when driving at a constant or slowly increasing speed the engine seems to lose power and won't pick up as normal (kind feels like a limp mode). Letting off the gas and reapplying throttle sometimes fixes it but not always. Runs great 95% of the time, but these things I know just aren't right.

A little more info., it fires up great, idles smooth, it's an auto (I know, I know -but it's a must for my 2 female drivers in th house plus it's a beach cruiser/commuter mainly). I have changed the AFM and DME to later eta spec (027 instead of 021).

Things I'm thinking are ground wires? (cleaned and replaced most main grounds within a year), AFM sweeper dead spots?, DME solder joints? I am running High imp. injectors for early etas (from what I understand high imp. injectors are okay with newer DME but not low imp. with older DME. There is a slight flow rate difference- lean condition?).

I'm kinda stumped but still pressing on. I can live with it this way, but I know it can be better so I am here asking for help.

[dnguyen1963]

One of the most missed troublesome spot in E30 is the elbows going into the throttle body. There is nothing to hold it tight until the engine creates vacuum. And this is a major problem because when it is in tight the engine starts easily and runs normally. However, when it is not tight then it might take a few cranks to start the engine. This is a classic problem of 1st crank no start then 2nd crank no problem. The elbow can also come loose if you drive over some bumps on the road to cause momentarily loss of power then everything is back to normal again. The fix is very simple...just JG weld the elbows into the throttle body and never have to worry about it again.

[e30patalohas]

Thanks D I will definitely do that tomorrow. Do you think RTV would do the same as JB?

[e30patalohas]

I also notice that the brake booster line isn't exactly a tight squeeze maybe a little mcgyvering there would help as well.

[dnguyen1963]

JB is more permanent. Some users tried RTV then eventually turned to JB. It is a good idea for you to do a smoke test if you have already found some loose hoses.

[e30patalohas]

Just checking back. All throttle body connections are tight and secure.
Swapped DME with a 24-pin unit (previous had a 28-pin chip) and added a power chip. It runs smoother and has more power and better response with this set up and premium fuel. The engine still exhibits the cold engine bogging/stutter and when warm it will accelerate normally, except on sustained acceleration/cruising under load (going up an incline on the freeway) then it will have a loss of power which feels like it may be starving for fuel pressure/volume. When I release the gas pedal and re-apply it seems to have the power back for awhile until it "starves" again.

I discovered another problem which is that the engine isn't happy above 3000 rpms and will misfire/detonate? and not want to revmuch over 3000-3400 rpm.

Could it be a fuel relay? High pressure pump going bad and cutting out? Or maybe the high impedance injectors causing these symptoms? For comparison, the current high impedance injectors flow 155cc/min. vs. 196cc/min. for the low impedance stock ETA 0280150126 injectors.

I am cleaning the old injectors and will try reinstalling these and see what happens. One injector has a torn pintle cap will this affect anything?

[dnguyen1963]

ETA uses low impedance injectors. I would buy a re-build kit and refresh all of your injectors. Tee in a pressure gauge while driving. If your fuel pump is going bad you should see pressure fluctuation. Also check the sock from your fuel pump for clogs. Have you replaced your fuel filter? Torn pintle cap will alter the spray pattern. I would replace it.

[navytapaul]

sounds like you need a tps, mine would do the same thing until I changed it out for a working one. Kind of a sketchy trick, but I've heard of some people drilling a small hole in the lowest point of the tps to let the oil drain out that makes them go bad.

[e30patalohas]

Both good points. I have replaced the fuel filter and relocated it higher in the engine bay. I have also replaced the Priming pump with a high flow in-tank unit along with new external High pressure fuel pump within a years time.

This leads me to think TPS as well, along with low imp injectors for good measure. Will get a new pintle cap from parts store locally $5/injector for a refurb kit. I know for sure that the TB adjusting screw isn't at factory setting due to PO and I have it dialed in pretty good to click just as the butterfly opens...but that's me adjusting by the Bently.

Anyone know if the TPS from a 325i can swap with a 325e? because I have one handy.

Thanks.

[navytapaul]

Yes it will work

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

[shaferbm]

When swapping in a TPS, does one need to calibrate it?

[bddog]

Mine has a chip and acts up most times unless I use a fuel additive. I buy Lucas on Amazon for $20 a gallon. It will run like crap. I put the additive in and Bam- she is purring.

[shaferbm]

That sounds like a bandaid to me. If it has a chip, more likely than not, the chip contains a map for the ecu for 93 octane gasoline and wasn't intended to cause need for a fuel additive.

Also, to answer my own question, the TPS can be metered. The procedure is in the bentley manual.