+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Maintenance (https://www.superturbodiesel.com/std/forumdisplay.php?fid=22)
+--- Forum: General (https://www.superturbodiesel.com/std/forumdisplay.php?fid=4)
+--- Thread: Rough @ Idle but strong on acceleration (/showthread.php?tid=629)
Rough @ Idle but strong on acceleration - spheil - 08-24-2009
The subject pretty much sums it up. I was at a light and it started to run rough on acceleration at the lower RPM but still accelerated. But it was time for some service so I did a valve job, new injectors, fuel filters and a purge. Still have a rough idle and at lower RPM's but it really has some new found power on heavy acceleration. Any ideas on lower RPM poor performance? It seems to have plenty of fuel. Could the fuel pump timing just change over time? I don't see any sign of exhaust leaks.
RE: Rough @ Idle but strong on acceleration - willbhere4u - 08-24-2009
What shape are the motor mounts and engine dampers? I had bad ones on a car that made it shake a lot at idle It had great power though! they are slow until boost kicks in I turned up the ALDA for low end power turn the screw ccw until it stops and then back cw just a tad and lock it down! and make sure the port in the back of the manifold isn't plugged! it adds fuel under boost!
I bypassed the ALDA over boost solenoid by running the boost line from the manifold straight to the ALDA so I could run more than 8psi boost
RE: Rough @ Idle but strong on acceleration - greasenut - 08-25-2009
I'll second the motor mount. My 82 300D shook very bad when the driver side mount gave up. It ended up coming out it two pieces and the rubber was very soft due to getting diesel spilled on it all those years. If you grab the valve cover and try to shake the motor, it should shake. If it feels like one of the mounts is sitting steel-on-steel, one of them probably is. A note of caution... when mine went south, one of the belts (power steering I believe) started to rub the oil cooler line, and the line had to be replaced (what a pain). If this happens to you, the oil cooler lines are easy to replace if the driver side motor mount is out - a pin if it is not. I ended up replacing the cooler lines the weekend after the motor mounts - bad timing on my part.
Also, if you could put info on your car in your sig, it helps those with the same car give advice. Good luck.
RE: Rough @ Idle but strong on acceleration - winmutt - 08-25-2009
Did you adjust the rack dampener? Might be the IP. Did you poptest the injectors?
RE: Rough @ Idle but strong on acceleration - spheil - 08-25-2009
It's funny that you say this I have new motor/trans mount as well as motor shocks/mounts and I haven't put them on because of this problem. I don't think they are the problem because it's more of an engine "miss" at idle and lower rpm's and today seemed to be at higher rpms. I'm going to look at the fuel tank filter tonight. And then the lift pump but not sure how to tell if the lift pump is working or not?
(08-25-2009, 10:10 AM)winmutt Did you adjust the rack dampener? Might be the IP. Did you poptest the injectors?
Not sure what the rack dampener is ( is it the spring on the back of the IP?). And when I rebuilt the injectors they pop at 1950 and when I bleed the line all injectors leaked fuel. What do you think of my fuel tank screen needing cleaning or the lift pump? The IP pump is $$$$
RE: Rough @ Idle but strong on acceleration - TotalDiesel - 08-25-2009
I have heard that bypassing the ALDA boost solenoid is a bad thing and can cause severe engine damage. Is this true? does it give more power? If I do this will it trash my engine or give it power or neither?
RE: Rough @ Idle but strong on acceleration - willbhere4u - 08-25-2009
all the ALDA dose is lean out the fuel mix at idle to prevent smoke when you floor it out of a light! If you set it rich it puffs some smoke at take off but doesn't add more power on the top end just a bit before boost hits!
if the banjo bolt on the manifold or the line to the ALDA is plugged broken or the solenoid are broken it leans the car out and feels like there is no turbo! = slow
The little electric actuator on the fire wall that runs to the ALDA on the injection pump doesn't let boost to the alda if the engine hits more than 8psi to lower power out put by reducing fuel! the sensor on the back top of the intake manifold is the pressure switch I disconnected the switch and removed the solenoid and just ran the boost line straight from the intake manifold to the ALDA so I could set my boost pressure to 10psi or higher I have seen these cars run 15psi with no problems!
RE: Rough @ Idle but strong on acceleration - winmutt - 08-26-2009
Some of this is incorrect. The overboost solenoid opens at 16psi, stock pressure for the turbo is 11.6psi.
I found my wastegate hose had rotted away sometime during the 6mos or so I spend without a boost gauge. Didn't notice it until the car was laboring a bit after coming to a stop on a 200+mile drive. Its more dangerous for the turbo than anything else with a stock pump.
RE: Rough @ Idle but strong on acceleration - TotalDiesel - 08-26-2009
okay well this is great information but the question still stands: Is bypassing the boost solenoid good or bad? will it help me or not?
I have also seen people completely rid the alda. I would prefer to do this because i want the most basic engine possible in my car and i dont want all the extra complicated garbage. I also wonder what the black box is on top of my valve cover. it is connected to the linkage and has hoses from the egr and water pump to it and out to the alda. I have seen many cars where that was removed too, whats the purpose of that??