Just finished a b16 swap in a 91 hatch. It runs well, the idle very slightly bounces from around 800 to 900 though.

My problem is if I run the car til its warmed up completely, then shut it off and start it again, at any rpm if I'm under about 5 percent throttle theres a dead spot as it cruises along it hitches. so if I'm just barely on the throttle it will just cut out til the car slows down a little then it will lurch forward.

Also if I turn the car off while its doing this it won't start again for a few minutes or until I pull the battery cable. No cel though.

If your on the gas a little it runs smooth and strong. If I never turn the car off and start it again warm it runs great.

 

sounds like the tps sensor to me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SFlCrx &raquo;</TD></TR><TR><TD CLASS="quote">sounds like the tps sensor to me</TD></TR></TABLE>I don't know, but I'm in for responses because my car does the same thing. But it only does it sometimes and it will only do it once right after the car has warmed up and then it won't do it again until the car gets shut off and warms up again. Then it might not happen again after that for another week. It's strange.

Edit: I guess mine isn't the same problem because mine has never had a problem starting again, but sometimes I do get a dead spot at partial throttle, I give it a little more gas and it lurches forward and all is well for another week or two.

 

sounds like your problem is the same as mine, just not as developed. I'll check my tps and keep you posted.

 

Yeah I would guess tps but it could be other things as well. Just thinking out loud the ecu uses inputs from you tps and map sensor as well as you intake air temp and coolant sensors to tell your injectors how much fuel and what ignition timing to run at any given situation. When you push down the throttle there is also a tip-in fuel enrichment. Blaa blaaa……. So I would start with checking your tps and check for vacuum leaks also check to make sure you have your map sensor hooked up to the right port if it is the firewall mount verity. If you stand on the passengers side of your car and look at the throttle body it hose on the upper right should go directly to you map sensor. Set your initial timing to make sure your dizzy is synced with the ecu, be sure to jump the service port when you do. That should be a good starting point.

 

how about the O2 sensor or sensors depending on your obd setup?

 

The o2 sensor isn't a factor. I had a brand new one in and I just switched to a crome ecu so I'm running closed loop now.

Since I have switched to crome (or put some miles on the car I'm not sure which caused this) my problem changed, it will still do the dead spot in the throttle but very very rarely now and not nearly as violently. The idle bounces sometimes now, I cleaned the pcv valve and the idle didn't bounce as much and driveability seemed to increase a little.


now it seems that the problem is only happens occasionally and half the time my car idles perfect and drives perfect... I haven't checked the tps yet but I'm starting to think that it may be the iacv I'll test the tps soon and change out the iacv for a known good part and tell you all the results

 

you should read up on crome, it would help you alot. good luck.

 

Thanks

 

Before you said you were on crome I was going to post it was a closed loop open loop transition problem, but since you are always on closed loop, you might need some more tuning, or as stated earlier check all sensors. I think when in closed loop it only looks at certain parameters, read up on crome

 

I will definately do some reading on on it.. I've been meaning to anyway. Thanks a lot for everyones help..

Also a tip-in fuel enrichment was mentioned earlier, I don't know what this is or how it works does anyone have a link to information on it?

 

When to punch the throttle the ecu tells the injectors to squirt in a little extra fuel, if you had or have a wideband you can see you fuel instantly get richer when you get on the gas. In crome when you add fuel tools there is an adjustment where you can scale up or down the amount of fuel added.
When I was tuning my boosted b16 after all the basic adjustment where made, I needed to scale it back a little bit. With crome pro you can seen your engine run in real time and also see many sensor parameters to include the tps.
Honestly I would start with the tps. I would also immerge myself in some serious reading. Why are you running crome in the first place? A stock ecu would work fine if our running a stock motor, don’t get me wrong crome is a great rom editor but you need to understand it a bit to get much out of it.

 

I know I am unread on crome. I needed some sort of fuel management because for me it was my first step toward boosting this motor. In the next couple of months I hope to turbo this car. (it will be my first turbo car) I was planning on next payday weekend when I'm ready to buy injectors sitting down doing all the reading over everything and planning out the kit I will build.

I'll check the tps tomorrow after work. Thanks again for all your help so far.

 

so are you buring your own chips then? i would recommend getting crome pro and a wideband to start off with. feel free to pm me with any questions on setting up your rom, if i can help, i will.

 

I had been planning on burning my own chips but was wondering how the romulators worked and so on. After reading more at pgmfi (as much as I can the wiki is down) I decided to take your advice and get crome pro, an ostrich and wideband.

I've been working a lot of hours and haven't had time to work on my car but I have the next couple of days off so I'll be posting the verdict on the tps very soon.

thanks for your offer, I'm sure I'll take you up on it when I'm more informed and have some intelligent questions for you.

 

I tested the tps (pain in the *** by yourself) and I think it is ok. I had a new cap but the rotor was old apparently (bought dizzy off a friend) replaced the extremely worn rotor and the car runs better (big surprise) still wanted to lurch a little and idle was still bouncy so I changed out the pcv
I've only ran the car for a couple of minutes but the idle seems to be perfect now... I had cleaned out the pcv prior to this but after rattling around a brand new part, it was obvious mine was roached.

I haven't driven the car so I don't know how it will act now, I'll update again soon

I plan on swapping the iacv and the tps with a friends this weekend if the problem isn't already corrected. Thanks to all of you for your help

 

I fixed this problem. My cam timing was off. I feel pretty stupid, I should have checked all the fundemental things first. Thanks for all the help