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I installed the new computer and MAF yesterday and I have some driveability issues. Okay, before the computer and MAF the car was running on the DE computer and MAF just fine, but really really rich. had tons of bottom end and very good driveability overall. Problem is, I installed the new computer and MAF and the car feels really good when you beat the hell out of it.
The car just seems to misfire at low rpm under load in any gear. It did not do this before the new maf and computer were installed. The car will be fine and will accelerate normal if given only a little throttle, but if you depress the pedal too far the car will lose power and not want to go. Sometimes the car seems to hesitate too but all this goes away if you go above 3500 rpm. It threw the CEL with a code stating "ignition malfunction or misfire" not stating which cylinder.
The only thing I changed with the car is the timing which is at ~15 degrees, TPS is .49 closed and 4.0 V at WOT. I was thinking the MAF might be fried or not reading correctly. I have heard of similar problems when the car is cold, but this happens all the time. If you have any suggestions please help. I was thinking about having the MAF cleaned out with some special cleaner but I am not sure the MAF is the problem because it idles perfectly.
Okay, I searched but can't find any solutions to my problem.
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99 SE-L. Graphite Gray GT3076R turbo, Protech Mani, 3" all the way! Nismo FPR 740cc, 255 pump, JWT computer,400whp pump is the goal.
Just so you know somebody's reading. I haven't seen this. If in fact the only two variables you changed were the ecu and maf, so given it's a new jwt ecu you'd suspect the maf, BUT you got an ignition code, which leaves out the maf. Only thing I can think of is to make sure you didn't push the ecu connector on crosseyed, and look around to make sure you have no loose connectors on the stuff next to the ecu connector.
Just for the hell of it, shut 'er off, disconnect the battery ground. Leave unhooked for 30 seconds. Hook it back up; this teaches the ecu to start learning all over again (about 30 starts for the full learning curve, as I remember). You could also have it at idle, unhook the connector from the tps; in about 5 seconds the ecu will figure out that the tps isn't there and drop the idle. It SHOULD still idle at about 600-750 if you have things set up correctly. Plug it back in still running, it'll start again to figure things out. Pretty sure you don't have to do this in addition to pulling the ground cable, that should also do the tps reset. Pulling the tps connector like that is a good thing to do once a season so the ecu gets to relearn each major weather change.
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'93 B13, etc.
If you don't have the patience
to do it right the first time,
how is it you have the time to
do it over and over again?
Ya the computer is installed correctly, car would probably not run otherwise. But I read in some other threads that the VE ECU pulls timing. I really really don't wanna go back to the stock ECU and change injectors after spending so much on the New computer. Maybe I will call andre and see if he knows anything. But keep posting if you guys have any suggestions. It seems that eric96ser and teal97 have had similar problems.
I would also check the maf. It's the most sensitive sensor on the car and would cause a lot of driviability problem. I noticed most of the people that swap the maf are the ones with the most driviabillity problem. Cutting and splicing wires isn't exactly good for electronic.
ok, looks like cleaning it did a whole lotta nothing, but I WILL find the problem. Also, I had my TPS voltage at .49V closed and 4.0 V WOT, but when I changed the computer it seems the reference voltage changed. I am only getting about .35V closed and WOT is only 3.15V. I will ground the MAF and see if the TPS is going to sh*t and get back with this one.
if this happens when its cold I would replace coolant temp sensor. Partial warm up readings are wrong gives ecu bad signal. sensor is only a few bucks. also 02 could be bad from running too rich for a long period of time.
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06 monaro cv8
91 ser 311whp@15psi
92 nx 185 whp all motor sold!!
sr20ve in the House with some freeze
CT SUPERHERO
Well I know the o2 sensor is bad, but that won't affect anything at WOT when the computer doesn't give a crap about the O2. I checked the tps voltage and it was lower than before the computer swap. I called up JWT and they said to look at their tech bullitin on their site where they have "instructions" to perform the computer swap. I didn't know you have to change some pins and stuff so I will have to do what it says there and see what happens.
I decided to advance the timing yesterday to see if I could get that low end stumbling to go away. Guess what? BOOM!!!!
Just kidding, no the stumble went away and I listened for detonation under different loads and rpm and so far so good. The car runs very well. I am not saying this will fix all of everyone's problems with the JWT computer with the VE program, but it has fixed my problem.
I am sitting at 25 btdc, no signs of detonation on 91 octane. I will see how far I can retard the timing before the car starts to stumble again. But the car has amazing bottom end power like it did before I changed the computer.
But here is another question... The car was sitting at 25 advance before the computer swap and had the same power it seemed like. But the car lost power up top. But now the car has about the same power down low as before, but keeps pulling to 8000 rpm. What do you guys think?
Very strange. Did you reset the tps voltage at closed throttle to .48 or so? 25* timing in idle mode (I presume) should be WAY too much; jwt wants 15 base with 93 octane. And I didn't get moving pins - I just plugged mine in and drove. (???) Switch is set for 4600 for my particular setup; I do need to try 4800.
Jer
well, the tps voltage is around .5 closed and is 4.19 at WOT. Which is a little on the high side. I know JWT recommended the timing to be at 15 btdc but BIG TOM suggested I try this and it works! Maybe they didn't change the timing maps on some of these VE computers like they should have? I don't know, but I do know that the car has a lot more torque than before and the bottom end hiccups are hardly noticeable anymore. The car feels great, however I am at an elevation of about 4500 feet. So keep that in mind.
Jim Wolfs VE program has been known to have drivability issues. Ditch that ECU and run something else.
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Blair
93 P10
"For I know the plans I have for you," declares the LORD, "plans to prosper you and not to harm you, plans to give you hope and a future." - Jeremiah 29:11 (NIV)
I would but I really love the...um... 8000 rpms. But if I can get a Calum for no hassles and for cheap I would love to. If anyone has any info on the calum, by all means. I don't want to spend all day searching. But i won't spend over 300 for it.
just check out calum page down before at the bottom the the forum. He is just finishing up on the b14 sr20ve ecus. my ecu is programmed for sr20ve inj, maf, and dizzy. with 8200 rev limiter= price is 165(prototype, then 185 when produced) with your own ecu. Calum does not have a stack of ecu's righ now so it is best to have your own
So, can they program the 99 computer I have for the emissions deletions like the JWT? Also, the idle with the 99 computer was too high when cold, around 3k. The manners of the car are really good with the JWT.
