Help... EFI Engine problems

Toby,

I've never been involved with a Haltech system. But start with the basics, check your fuel pressure, is it dropping off, or too low to start with. 54 pound injectors are healthy injectors (possibly too big), but they need their rated pressure to provide their rated flow rate. Of course, check the pulse width (duty cycle) to the injectors to confirm they are within their electrical operating area too.
Check the condition of your spark plugs & finally scope the output of the coil. One of these checks should give you an idea where the problem lies.

Sorry I'm not more help.

Regarding the "EFI survey". One of these days I'll stick a system on my Pantera & show our community how it can be done, no headaches. Hint, think EEC IV.

George

George, Thanks for the ideas. I have checked Fuel pressure through out the rpm range and am staying steady at 50 psi. Yes the 54 pound injectors are healthy but are ok. I upgraded to the 54 pound, but did make a few runs on the dyno with 42 pound injectors and had the exact same problem at 5000rpm. The spark plugs have been replaced during the dyno runs and I have scoped the signal to the coil but not output to the dist. I have also scoped tach output from MSD to Haltech.
Regarding pulse width and duty cycle of the injectors. I ran a datalog during the last dyno run and the moment I cross the 4900rpm mark I get erratic readings. The pulse width is jumping from a good 6ms to as much as 13ms. The duty cycle also is jumping around from 35-80%. Something is giving the ECU some strange input readings. My first thought was the tach output from the MSD to Haltech. But that has been scoped and signal is clear. Maybe the haltech itself is dying??
Any more ideas?

Thanks Toby

Toby,

You're on the right track, if the signal to the injectors becomes erratic at 5000 rpm that is why your engine wont rev higher than that. I'm not sure what inputs there are into the Haltech, but each one needs to be checked individually to determine if any become erratic or just plain bad at 5000 rpm. The MSD is a possible culprit, but I'm sure there are other sensors, for instance throttle position and manifold pressure are also worth checking.

George

George, The tach output to the MSD has been scoped and looks fine, The other sensors are MAP, WTS, AIT, TPS. The TPS sensor is only there for the accelerator pump because i am running this system by Map. Water sensor is only active when cold to enrich and also when running hot to enrich. AIT makes minor adjustments but nothing that would throw the A/F ratios, Duty cycles, and pulse width around so much. I am really stuck on this one!

Toby

Toby,

It may be time to telephone Haltech. You haven't mentioned the MAP sensor. Since you are depending on that sensor to do most of the controlling, it should be checked. If nothing else, just monitor the voltage out of the sensor. Possibly it has a bad spot at a certain manifold pressure. Outside of that, I'm out of ideas.

To others reading this post, if this were an EEC IV system, it would have self diagnostics & would actually tell us which sensor was out of range. With a scanner, such as the Autoxray scanner, you can run real time trends on each individual sensor while the engine is running, including while you are driving the car, and visually check the performance of each sensor.

George

54 pound injector sounds real high. I am running a 351W stroked to 427 and it runs just 36 pound injectors in a multi-port setup on a vic Jr manifold running fuel rails.

The pulse width as indicated in a prior post is a critical measurement in the injectors load factor. If they are being over worked, or perhaps in your case, under worked, it could create fuel issues. Use this to judge the right sized injector, Like a carb too bad is as bad as too small.

You will need to use your laptop and look at every sensor. TBS, Man pressure etc, if one of the sensors is off or acting up it could create an inbalance. Also how does the fuel map look, nice and smooth with no peaks or valleys? Did you play with the spark map? Are you dialing in too much advance or retard at that RPM/Manifold pressure?

The good and bad about fuel injectors is the tunability too many knobs to twist.

Rover, thanks for the info. I know the injectors are quite high but I have been running 36lb injectors on the dyno as well. I have checked the sensors and everything is working properly. I did go ahead and switch MSD boxe. I also switched to TPS instead of MAP trigger. I am going to remap in TPS mode tomorrow and see if the same problem pops up again at 5000rpm. Take a look at the datalog from the last dyno run. Notice how everything is going haywire just above 4800 rpm once load is being applied which starts around line 25. The duty cycle and pulse width are all over the place. We shut the engine down at line 102.

Haltech Datalog 6/22/2005

Line# RPM Kpa Throt % Inj mS Duty%
1 2000 -52 3 2.176 7
2 2140 -48 3 2.136 7
3 2200 -47 4 2.176 8
4 2260 -48 4 2.288 9
5 2380 -43 4 2.248 9
6 2640 -40 5 2.2312 12
7 2820 -38 6 3.088 12
8 3140 -39 7 2.864 14
9 3520 -36 8 2.656 16
10 3960 -34 11 3.648 21
11 4320 -29 12 2.992 22
12 4400 -30 13 2.912 25
13 4840 -31 13 3.808 31
14 5200 -35 13 3.728 27
15 5200 -33 13 3.584 20
16 5140 -31 12 3.76 20
17 4960 -32 12 3.208 27
18 5020 -35 13 3.472 27
19 4840 -31 13 3.144 25
20 4840 -31 13 3.624 25
21 5020 -30 13 3.624 31
22 5140 -26 14 3.768 31
23 4580 -26 14 3.48 25
24 4840 -23 15 3.712 43
25 5020 -25 16 3.768 31
26 4840 -24 17 4.592 37
27 4840 -24 18 4.704 36
28 5080 -15 19 4.176 39
29 5020 -17 19 4.632 31
30 5080 -15 20 4.64 29
31 5400 -16 20 4.824 37
32 5280 -15 20 5.216 31
33 4960 -17 20 4.52 49
34 4760 -22 21 4.76 31
35 5280 -18 21 6.608 29
36 4840 -20 21 4.768 45
37 5020 -21 22 6.728 33
38 4960 -13 22 6.904 42
39 5140 -17 23 4.624 36
40 5080 -12 24 4.688 39
41 4840 -15 24 4.768 27
42 4900 -18 25 5.664 30
43 5020 -14 25 4.512 47
44 4900 -18 26 5.728 64
45 5020 -16 27 9.704 54
46 5020 -15 27 6.184 48
47 5140 -13 28 6.184 47
48 4960 -10 29 5.048 35
49 5020 -12 29 6.776 53
50 5580 -10 30 5.368 54
51 5580 -11 31 5.432 29
52 5460 -12 31 7.464 53
53 5280 -8 31 8.112 55
54 5200 -8 31 4.736 41
55 5340 -13 31 8.328 31
56 2500 -10 32 7.344 52
57 5340 -15 33 7.208 47
58 5280 -15 33 6.704 38
59 5080 -10 33 5.864 33
60 4900 -12 34 6.201 62
61 4760 -14 35 7.544 42
62 2380 -8 36 7.84 51
63 5020 -13 37 7.416 58
64 5140 -12 37 9.216 46
65 5020 -8 38 6.144 24
66 5140 -13 38 8.456 46
67 2440 -9 39 9.368 50
68 4840 -8 39 8.576 46
69 4960 -11 40 9.128 78
70 2380 -9 40 6.096 65
71 4900 -12 41 9.648 76
72 5140 -12 41 8.776 77
73 4840 -12 41 8.584 44
74 5020 -7 42 12.712 80
75 5080 -10 42 5.144 30
76 4900 -10 43 8.464 44
77 1640 -5 44 9.656 40
78 2380 -8 44 10.424 89
79 4840 -9 45 7.424 45
80 4900 -7 46 5.792 46
81 4760 -8 46 9.712 100
82 5140 -8 47 13.305 23
83 4840 -10 48 10.536 44
84 5020 -7 48 9.656 73
85 5140 -7 48 13.609 71
86 5140 -10 49 13.217 63
87 5200 -7 50 9.12 23
88 5460 -5 51 12.601 52
89 5140 -8 52 13.865 55
90 5140 -8 53 11.856 25
91 4760 -10 54 11.592 86
92 2500 -9 56 8.344 35
93 5140 -10 58 12.56 28
94 5140 -9 63 10.944 67
95 4840 -7 66 7.088 47
96 4840 -8 71 11.992 70
97 5020 -7 78 6.056 36
98 820 -9 87 12.904 63
99 5140 -7 91 6.208 60
100 4840 -6 91 14.537 65
101 5080 -4 91 11.992 61
102 4840 -12 49 12.441 22
103 3320 -67 4 2.68 13
104 2760 -59 4 2.13 9
105 2380 -52 4 2.201 8

Sorry the datalog did not post too well on the group, if you would like a clean version i can email it.
Thanks for all the help.

Toby

Make sure that that the scope you are using has enough bandwidth to be able to observe fast spikes that can falsely trigger the Haltech. Make sure the scope is grounded in a logical place close to the signal source.

Well, that is a hoot. Seems like the sensors are reading OK. Manifold pressure and throttle position seems to be in check throughout the pull. Somehow you are hitting an instable state where the computer is over correcting and bouncing around.

I have the same fuel pump and similiar MSD setup. What is not clear is the type of distributor. Do you have a electronic distributor that the Haltec controls? IF so, is the distributor in good shape and not changing spark advance or dropping an cylinder creating a mis-fire? A worth while check.

Look at the fuel map again if you have a lean out condition it could be hick-uping and throwing things into a unstable state. I can see why it lead you into the direction of bigger injectors, it acts like a lean condition.

Dumb question but is the plug wires and MSD unit far enough away from the ECU and injectors? Just the odd chance that you are hitting a EMI issue and the spark plugs are effecting sensor readings. Other then that I agree a call to Haltech is in order to narrow the field. I am stumped.

I think I have resolved the problem. It seems the tach output volts to the ecu were a bit on the low side for the Haltech. By adjusting the Haltech internal dipswitches i was able to lower the trigger input sensing voltage to +2.0v rather than the initial setting of +2.5v. I made a dyno pull this morning up to 6200rpm without any rpm hickups. I still have mapping to do in the higher rpm ranges but things look much better!

Thanks for all the help, and I will update with some torque and HP #rs soon.

Toby

Toby Grrreat!

Always feels good to resolve a problem that's been kicking you in the, uh, derriere.

Thanks for getting back to the BB regarding the solution. It's a let down to try to help somebody with their trouble & then they go silent, never sharing the outcome. Its how we all learn.

George