Engine/Transmission (1994 - 1998) less power at full throttle than 1/2 throttle

[jtwcummins]

When I removed my egr the intake was full of soot and blocking the vac to turbo. Wasn't able to get over 12 lbs boost. Cleaned out soot and jumps to 10 at part throttle and peaks about 30

 

[Joe G.]

Peak torque is at 1600 RPM. However, it will run hot EGT at that RPM while towing. I lock out OD when towing except on flat road with no head wind. No EGT problem at all. Even stock mine would turn 2700 RPM easy. You need to block anyway the exhaust can get to the intake. Jay sounds right to me. You may have to clean the intake manifold out to get it to stop sooting up things. I have 3. 54 gears so the MPH is pretty good with OD locked out.

 

[paulsmith]

I have 3. 54 gears also. But mine will not go above 55 mph, 59 tops on a down hill. Engine speed at 55 mph is well over 2000 rpm, and it just wont pull past 2200 rpm. That is floored, AND with my finger on the "accel" button on the cruise control! I did not buy a CTD to pull a 5000# load at 55 mph when the speed limit is 70. I had a 350 chevy that would do that. I have always known that both my trucks have a "dead spot" between 55 and 65 mph, so I dont pull there, I go 55 or 70.



Anyway, we may be getting off the point. I have totally REMOVED the Egr system, with a 1/4" plate over the exhaust hole and another over the intake hole. I relize the right thing to do would be to replace the manifolds for best performance, but, remember, this is normally my "hired driver" truck, so I just want "stock power". Both myself and my driver are concerned when we are going 39 mph through St Louis on I-55, when other traffic is going 70 mph in rush hour traffic.



I am not sure about jtwcummins comment about the vac to the turbo. I can see some left over soot in my intake, BUT, I have the hose completly disconnected from the turbo wastegate, so I should be getting whatever boost the fuel and engine can make.



I have cleaned the hose to the AFC, and have hooked a boost gauge to a tee directly on the AFC housing to confirm that it is in fact getting boost. To further confirm that the AFC is not the problem, I completly removed the AFC. this resulted in black smoke at take off, but no more power. I have manually applied 10 psi of air to the AFC and confirmed it works.



In fact, that is the ONLY time I have every seen this truck smoke (except when cold).



I get the feeling I am not getting full "stroke" of the throttle, or full governor, or the "thingy" is not following the fuel plate, or something. I have a #6 plate I think, I could put it in, but with the stock plate slid all the way to the front..... I dont think that is the answer.



One good side effect, i am almost to 200,000 miles on the orginal transmission!

 

[Andy Redmond]

Paul:



You likely have an air leak (boost) or low fueling.



I didn't take time to read many of the other posts from the beginning. Have you had someone apply air pressure at the turbo compressor inlet to check for innercooler leaks, boot leaks etc. then proper wastegate acuation, afc link movement at 15 psi or so? (See the posts in the archives on the homemade "Fernco" pipe coupler that many use).



The EGR system sounds suspect too. Assure that no blockages exist (carbon).



You have the classic low fuel symptoms too. More fuel equals more power...



Also carefully ck. the throttle linkage, is WOT really wide open? Incorrect linkage adjustment, thick floor mats etc can prevent throttle travel. You can look at the recall notice for the throttle cable and linkage for the 94-96 trucks on the dodgeram.org site. That or the FSM give specific detailed instructions on testing/adjusting the linkage for proper application. It would shock you how much that last 1/4" of movement at the pump can make. .



You mentioned that the afc removed netted only slightly more boost and black smoke. Low fueling likely. . ck. the transfer lift pump for volume and pressure if you haven't.



Also wire the shutdown solenoid up to assure full movement and that the hold coil isn't weak allowing for partial fueling.



Is the afc link binding (prevents full fueling).



Also a plugged torq. converter can choke even a healthy motor.



Good luck,

Andy

 

[Howard Durand]

I have heard about problems in the fuel tank itself preventing adequate fuel flow.

 

[paulsmith]

I have no drop in fuel pressure at WOT. I have checked and actually ran without the AFC installed. I have used a Ferco Adaptor on the turbo inlet and pressurized the air intake to 15 psi, it was like airing up a tire, no leaks. I checked and adjusted the fuel shut down for full stroke, but i will wire it up to insure full stroke, when I get a chance to park the truck again.

Paul

 

[Joe G.]

Paul,



I just remembered a problem I had several years ago. It may not apply here, but can't hurt to check. The linkage lever is fastened to the pump lever with a couple of little screws. 8mm head. I had one of them fall out. The other was still pretty tight, but it did allow the linkage lever to turn a little on the pump lever so the throttle acted strange.

 

[Willys]

Paul, I'm reading this thread because I'm looking for the cause of a somewhat similar low-power problem on my truck. I'm no guru, just learning in baby steps here, but I'm wondering if you've checked the throttle cable and throttle linkage for correct adjustments/lengths, and if you've checked the tps for proper voltage? Not that I think the TPS could cause low power, but that its part of the process of adjusting the linkage if my memory from reading the directions a few days ago serves me right...



Ok, another thing I've seen here a few times is the mention of a plugged Torque Converter??? Or was that a plugged cat...



Any updates?



Edit: Post 5 mentions the plugged torque converter, what's that mean?

 

[Willys]

Any updates?

 

[K5IP]

Sounds like your boost data is not far out of line for stock.

Here is data from my 95 (5spd). Taken with waste gate fooled, 5000FT elevation.

Original plate, original position. Original injectors (180), Wide open throtle.



2000 RPM 13 PSI boost pressure

2250 RPM 15 PSI

2600 RPM 16 PSI (max boost obtainable at this altitude)



After upgreda to 215 injectors:

2000 RPM 15 PSI

2250 RPM 17 PSI

2600 RPM 19 PSI (max obtainable)



After installing 3Kgsk

2000 RPM 11 PSI

2250 RPM no data

2600 RPM 15 PSI

2900 RPM 20 PSI



Note that installatioin of the 3kgsk actually reduced fueling in the midrange.

After consulting Piers and Joe D,

Moved original plate . 020 forward, Now:



2000 RPM 15 PSI

2250 RPM 17 PSI

2500 RPM 19 PSI

2900 RPM 21 PSI



Note that boost is a function of both fueling and RPM. (and indirectly, horsepower)

Boost data taken at sea level would of course be higher. Keeping your own record of boost performance for youor engine can help make you aware of changes (like air leaks). It certainly made me aware that something had deteriorated when I installed the 3GSK.

Rog



Rog











After upgred

 

[Andy Redmond]

Plugged auto transmission torque converter (possibly reused after a trans rebuild where major parts have grenaded or trash or wear particles that restrict fluid flow).



I have spent a lot of time with a truck that has an early "performance=low stall" converter from a TDR vendor vintage 1998. My how all of thier products have improved. In defense of the vendor their parts were installed by a somewhat dis-reputable trans shop in the area. The truck was operated commercially for several years and when it started running poorly I got a phone call. .



Anyhow it just sucks the life out of the old 12v and brings it to its knees. The engine is sound and performing well.



Occasionally the truck will tear off from a start and spin the tires (its owner is used to wot to achieve any movement). Most of the time its very sluggish.



A friend in the transmission business helped with trans diagnosis after I gave the 12 v a clean bill of health (manometer test, compression test, fuel tests, fuel air leaks, etc. even swapped p7100 with another know pump that was juiced with little difference).



Anyhow, was just relaying another possible problem. Lets hope the transmission is ok and not the issue.

 

[Willys]

Andy, Thanks for the info, that explains a lot...



I've also seen mention of a leaking torque converter, can you shed some light on that?



The symptoms you describe are much like my truck, but I'm still going through some (slow) tests...



K5IP, that is a good point to make- you have to have a benchmark(baseline) to go by (various issues of the TDR make this point)

 

[EGILLILAND]

Paul,



I just remembered a problem I had several years ago. It may not apply here, but can't hurt to check. The linkage lever is fastened to the pump lever with a couple of little screws. 8mm head. I had one of them fall out. The other was still pretty tight, but it did allow the linkage lever to turn a little on the pump lever so the throttle acted strange.

Hey Joe... any chance you could point out where these little bolts/screws were on this pic?

 

[biggy238]

My guess is the left side (front of engine) of the throttle control rod. Your throttle cable attaches there. Might have a TPS bolted over it if automatic truck.

The linkage looks like the Gov assembly might not follow what the front of the pump is doing if the control rod if loose. It could be your problem.

 

[Joe G.]

Hey Joe... any chance you could point out where these little bolts/screws were on this pic?

Look at the throttle control rod. On the right end of it in the picture it attaches to a little ball. That ball is mounted on a lever. That lever is fastened to the pump lever with two screws.

 

[Andy Redmond]

Willys:



Leaking thru the hub? or internal damage that doesn't route the fluid where is should run over the stator etc.



Get a FSM and look at the trans section, I think it shows a cut-away of the internals of the trans as well of the torq. converter.





Biggy:



See attached part # 20 is what Joe refers to... (sorry its flipped, I can never seem to attach a file w/out cropping furiously, I guess you can export it to your hd and open it in window paint etc. then rotate so you don't have to tilt your head).



If you don't have a 215 pump some of these parts may look a little diff on your 160, 175,180 pumps.



Good luck

Andy

 

[biggy238]

I was close. . wrong end though. I'm going to check mine out next time i'm there.

 

[Willys]

Andy,

I don't think I've been getting all the email updates lately when someone posts a response. I think I'd seen someone mention that the torque converter itself could leak, I thought it was in this thread but I could be mistaken. I'll have to do some reading in the FSM to see if I can find it...